Intraocular lens that improves overall vision where there is a local loss of retinal function

ABSTRACT

Systems and methods are provided for improving overall vision in patients suffering from a loss of vision in a portion of the retina (e.g., loss of central vision) by providing symmetric or asymmetric optic with aspheric surface which redirects and/or focuses light incident on the eye at oblique angles onto a peripheral retinal location. The intraocular lens can include a redirection element (e.g., a prism, a diffractive element, or an optical component with a decentered GRIN profile) configured to direct incident light along a deflected optical axis and to focus an image at a location on the peripheral retina. Optical properties of the intraocular lens can be configured to improve or reduce peripheral errors at the location on the peripheral retina. One or more surfaces of the intraocular lens can be a toric surface, a higher order aspheric surface, an aspheric Zernike surface or a Biconic Zernike surface to reduce optical errors in an image produced at a peripheral retinal location by light incident at oblique angles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. §119(e) of U.S.Provisional Application No. 61/950,757, filed on Mar. 10, 2014, titled“INTRAOCULAR LENS THAT IMPROVES OVERALL VISION WHERE THERE IS A LOSS OFCENTRAL VISION.” This application also claims benefit under 35 U.S.C.§119(e) of U.S. Provisional Application No. 61/987,647, filed on May 2,2014. The entire content of each of the above identified applications isincorporated by reference herein in its entirety for all it disclosesand is made part of this specification.

This application is also related to U.S. application Ser. No. ______,filed concurrently herewith on Mar. 10, 2015, titled “DUAL-OPTICINTRAOCULAR LENS THAT IMPROVES OVERALL VISION WHERE THERE IS A LOCALLOSS OF RETINAL FUNCTION,” Attorney Docket No. AMOLNS.055A1. Thisapplication is also related to U.S. application Ser. No. ______, filedconcurrently herewith on Mar. 10, 2015, titled “ENHANCED TORIC LENS THATIMPROVES OVERALL VISION WHERE THERE IS A LOCAL LOSS OF RETINALFUNCTION,” Attorney Docket No. AMOLNS.055A2. This application is alsorelated to U.S. application Ser. No. ______, filed concurrently herewithon Mar. 10, 2015, titled “PIGGYBACK INTRAOCULAR LENS THAT IMPROVESOVERALL VISION WHERE THERE IS A LOCAL LOSS OF RETINAL FUNCTION,”Attorney Docket No. AMOLNS.055A3. The entire content of each of theabove identified applications is incorporated by reference herein in itsentirety for all it discloses and is made part of this specification.

BACKGROUND

1. Field

This disclosure generally relates to using an intraocular lens toimprove overall vision where there is a local loss of retinal function(e.g., loss of central vision due to a central scotoma), and moreparticularly to using an intraocular lens to focus light incident atoblique angles on the patient's eye onto a location of the peripheralretina.

2. Description of Related Art

Surgery on the human eye has become commonplace in recent years. Manypatients pursue eye surgery to treat an adverse eye condition, such ascataract, myopia and presbyopia. One eye condition that can be treatedsurgically is age-related macular degeneration (AMD). Other retinaldisorders affect younger patients. Examples of such diseases includeStargardt disease and Best disease. Also, a reverse form of retinitispigmentosa produces an initial degradation of central vision. A patientwith AMD suffers from a loss of vision in the central visual field dueto damage to the retina. Patients with AMD rely on their peripheralvision for accomplishing daily activities. A major cause of AMD isretinal detachment which can occur due to accumulation of cellulardebris between the retina and the vascular layer of the eye (alsoreferred to as “choroid”) or due to growth of blood vessels from thechoroid behind the retina. In one type of AMD, damage to the macula canbe arrested with the use of medicine and/or laser treatment if detectedearly. If the degradation of the retina can be halted a sustained visionbenefit can be obtained with an IOL. For patients with continueddegradation in the retina a vision benefit is provided at least for atime.

SUMMARY

The systems, methods and devices of the disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

Ophthalmic devices that magnify images on the retina can be used toimprove vision in patients suffering from AMD. Such ophthalmic devicescan include a high optical power loupe or a telescope. Intraocularlenses (IOLs) that magnify images on the retina can also be implanted toimprove vision in patients suffering from AMD. Such IOLs are based on atelescopic effect and can magnify images between about 1.3 times andabout 2.5 times, which will improve resolution at the cost of a reducedvisual field. However, such IOLs may not provide increased contrastsensitivity.

Various embodiments disclosed herein include ophthalmic devices (suchas, for example, IOLs, contact lenses, etc.) that take intoconsideration the retinal structure and image processing capabilities ofthe peripheral retina to improve vision in patients suffering from AMD.The ophthalmic devices described herein can be lightweight and compact.Various embodiments of the ophthalmic devices described herein can focusincident light at a preferred area of the peripheral retina. Variousembodiments of the ophthalmic devices described herein can correct foroptical errors occurring in the image formed in the area of theperipheral retina due to optical effects such as oblique astigmatism andcoma.

The embodiments described herein are directed to ophthalmic lenses, suchas an IOL, and a system and method relating to providing ophthalmiclenses that can improve visual acuity and/or contrast sensitivity whenthere is a loss of central vision by focusing incident light onto anarea on the peripheral retina where vision is best. Such ophthalmiclenses can include refractive structures such as prisms and diffractivestructures such as gratings to focus incident light onto the preferredretinal location.

One aspect of the subject matter described in this disclosure can beimplemented in an intraocular lens configured to improve vision for eyeshaving no or reduced foveal vision. The intraocular lens comprises afirst zone having an optical axis which intersects the retina of the eyeat a location external to the fovea; and a second zone having an opticalaxis which intersects the retina of the eye at the fovea, wherein thefirst zone has a power that is greater than the second zone. Embodimentsfurther include an intraocular lens comprised of an optic configured toprovide multi-refraction for focusing light on an area surrounding aPRL. The intraocular lens may be comprised of two refractions, whereinone of the two refractions is in the horizontal field and the other ofthe two refractions is in the vertical field. It is also envisioned thatthe multi-refraction may be comprised of a continuous refraction for ahorizontal line below or above a scotoma. Or, the multi-refraction maybe comprised of a horizontal line on both sides of the scotoma. It isfurther envisioned that one surface of the optic may be comprised ofeither a multifocal pattern or an extended depth of focus pattern.

Another aspect of the subject matter described in this disclosure can beimplemented in a method for improving vision where there is no orreduced foveal vision using an intraocular lens with at least two zones.The method comprising: determining a deflected optical axis whichintersects a retina of a user at a preferred retinal locus; modifying afirst zone of the intraocular lens to redirect incident light along thedeflected optical axis; modifying a second zone of the intraocular lensto direct incident light along an undeflected optical axis whichintersects a retina of a user at the fovea; and adjusting a power of thefirst zone to be greater than a power of the second zone.

One aspect of the subject matter described in this disclosure can beimplemented in an intraocular lens configured to improve vision wherethere is a loss of retinal function (e.g., a loss of foveal vision), theintraocular lens comprising: a redirection element configured toredirect incident light along a deflected optical axis which intersectsa retina of a user at a preferred retinal locus. The redirection elementcomprises a surface with a slope profile that is tailored such that, inuse, the intraocular lens: redirects incident light along the deflectedoptical axis; focuses the incident light at the preferred retinal locus;and reduces optical wavefront errors, wherein the slope profile istailored to redirect and focus the incoming rays on the preferredretinal locus. The slope profile can be tailored based at least in parton a solution to an analytical equation that is a function of a distancefrom the IOL vertex to the original focus (l), an index of refraction ofthe IOL (n_(l)), an index of refraction of the aqueous environment(n_(aq)), an angle inside the eye to the preferred retinal locusrelative to a back vertex of the IOL (a_(p)), a radial position of theIOL (x), and/or the posterior radius of curvature of the IOL (r), theanalytical equation given by the following:

${{{slope}(x)} = {- {\cos^{- 1}\left( \frac{{n_{aq}\cos \; \alpha} - {n_{l}\cos \; \beta}}{\sqrt{{n_{aq}^{2} + n_{l}^{2} - {2\; n_{aq}n_{l}\sin \; \alpha \; \sin \; \beta} - {2\; n_{aq}n_{l}\cos \; \alpha \; \cos \; \beta}}\;}} \right)}}},$

wherein

${\alpha = {\tan^{- 1}\left( \frac{{l\; \sin \; a_{p}} - x}{{l\; \cos \; a_{p}} - r - \sqrt{r^{2} - x^{2}}} \right)}},$

and wherein

$\beta = {{\sin^{- 1}\left( {\frac{n_{aq}}{n_{l}}{\sin \left( {{\tan^{- 1}\left( \frac{- x}{l - r - \sqrt{r^{2} - x^{2}}} \right)} + {\sin^{- 1}\left( \frac{x}{r} \right)}} \right)}} \right)}.}$

In some implementations, the slope profile can be tailored based atleast in part on an analytical solution to an equation describing an eyeof a patient. In some implementations, the slope profile can be tailoredbased at least in part on simulations performed using ray tracingtechniques. In some implementations, the slope profile can be determinedanalytically using an equation that incorporates an axial length to thepreferred retinal locus, an angle of the deflected optical axis relativeto an undeflected optical axis, and a radial position of the preferredretinal locus. In various implementations, the slope profile can betailored using an iterative procedure that adjusts a portion of theslope profile to account for a thickness of the redirection element.

The redirection element can comprise a plurality of zones. Each zone canhave a slope profile that is tailored based at least in part on thesolution to an equation (e.g., the analytical equation given above). Invarious implementations, a thickness of the redirection element can beless than or equal to 0.5 mm. In various implementations, a curvature ofa posterior surface of the intraocular lens is configured to provide afocused image at the fovea of the retina of the patient. In variousimplementations, the redirection element can be a separate, additionalsurface on the intraocular lens. In some implementations, theredirection element can be a ring structure. In some implementations,the redirection element can cover a central portion of the intraocularlens. The central portion can have a diameter that is greater than orequal to 1.5 mm and less than or equal to 4.5 mm. In variousimplementations, a posterior surface of the intraocular lens can includethe redirection element, and an anterior surface of the intraocular lenscan include a second redirection element comprising a plurality ofzones, each zone having a slope. In some implementations, a posteriorsurface and/or an anterior surface of the intraocular lens can be toric,aspheric, higher order aspheric, a Zernike surface or some other complexsurface. In various implementations, the posterior surface and/or theanterior surface of the IOL can be configured to reduce astigmatism andcoma in the focused image produced at the preferred retinal locus. Invarious implementations, a portion of the IOL can include theredirection element and another portion of the IOL can be devoid of theredirection element. In such implementations, the portion of the IOLincluding the redirection element can have an optical power that isdifferent from the portion of the IOL that is devoid of the redirectionelement.

Another aspect of the subject matter described in this disclosure can beimplemented in a method for improving vision where there is no orreduced foveal vision using an intraocular lens and a redirectionelement having a tailored slope profile. The method comprising:determining a deflected optical axis which intersects a retina of a userat a preferred retinal locus; calculating a tailored slope profile forthe redirection element, the tailored slope profile comprising aplurality of slope values calculated at a corresponding plurality ofpoints on a surface of the intraocular lens; determining opticalaberrations at the preferred retinal locus based at least in part onredirecting light using the redirection element with the tailored slopeprofile; adjusting the slope profile to account for a thickness of theredirection element; and determining whether a quality of an imageproduced by the redirection element with the adjusted tailored slopeprofile is within a targeted range.

One aspect of the subject matter described in this disclosure can beimplemented in a method of using an intraocular lens to improve opticalquality at a preferred retinal locus, the method comprising: obtainingan axial length along an optical axis from a cornea to a retina;obtaining an axial length along an axis which deviates from the opticalaxis and intersects the retina at the preferred retinal locus. Themethod further comprises determining a corneal power based at least inpart on measurements of topography of the cornea; estimating an axialposition of the intraocular lens wherein the intraocular lens withinitial optical properties at the estimated axial position is configuredto provide a focused image at a fovea. The method further comprisesadjusting the initial optical properties of the intraocular lens toprovide adjusted optical properties, the adjusted optical propertiesbased at least in part on the axial length along the optical axis, theaxial length along the deviated axis to the preferred retinal locus, andthe corneal power, wherein the adjusted optical properties areconfigured to reduce peripheral errors at the preferred retinal locationin relation to the intraocular lens with the initial optical properties.

Another aspect of the subject matter described in this disclosure can beimplemented in an ophthalmic device configured to deflect incident lightaway from the fovea to a desired location of the peripheral retina. Thedevice comprises an optical lens including an anterior optical surfaceconfigured to receive the incident light, a posterior optical surfacethrough which incident light exits the optical lens and an axisintersecting the anterior surface and posterior surface, the opticallens being rotationally symmetric about the axis. The device furthercomprises an optical component disposed adjacent the anterior or theposterior surface of the optical lens, the optical component having asurface with a refractive index profile that is asymmetric about theaxis.

One aspect of the subject matter described in this disclosure can beimplemented in an ophthalmic device comprising an optical lens includingan anterior optical surface configured to receive the incident light, aposterior optical surface through which incident light exits the opticallens and an optical axis intersecting the anterior surface and posteriorsurface. The device further comprises an optical component disposedadjacent the anterior or the posterior surface of the optical lens, theoptical component including a diffractive element, wherein the opticalcomponent is configured to deflect incident light away from the fovea toa desired location of the peripheral retina.

Various implementations disclosed herein are directed towards anintraocular device (e.g, an intraocular lens, an ophthalmic solution, alaser ablation pattern, etc.) that improves visual acuity and contrastsensitivity for patients with central visual field loss, taking intoaccount visual field, distortion or magnification of the image. Thedevice can be configured to improve visual acuity and contrastsensitivity for patients with AMD through specific correction of theoptical errors for the still healthy retina that the patient uses forviewing. The device can be configured to correct peripheral errors ofthe retina with or without providing added magnification. The device canbe configured to correct peripheral errors of the retina either withoutfield loss or in combination with magnification. The device can beconfigured to include a near vision zone. The device can be configuredto include multiple optical zones with add power. In variousimplementations, wherein the device is configured to focus lightincident in a large patch including a plurality of angles of incidenceis focused in a relatively small area of the retina such that the imagehas sufficient contrast sensitivity. In various implementations, lightincident from a plurality of angles of incidence are focused by thedevice as an extended horizontal reading zone above or below the fovea.In various implementations, light incident from a plurality of angles ofincidence are focused by the device in an area surrounding the fovea andextending upto the full extent of the peripheral visual field. Invarious implementations, the device is configured to provide sufficientcontrast sensitivity for light focused at the fovea for patients withearly stages of macular degeneration.

Various implementations of the device can include a redirection elementthat is configured to redirect incident light towards a peripheralretinal location. Various implementations of the device can includesymmetric lenses surfaces with aspheric surfaces. Variousimplementations of the device can include asymmetric lenses surfaceswith aspheric surfaces. Various implementations of the device caninclude asymmetric/symmetric lenses surfaces with aspheric surfaceshaving curvatures such that when implanted in the eye a distance betweenthe anterior surface of the lens and the pupil is between 2 mm and about4 mm and the image formed at a peripheral retinal location at aneccentricity between 7-13 degrees has an average MTF greater than 0.7for a spatial frequency of about 30 cycles/mm. The aspheric surfaces invarious implementations the device can include higher order asphericterms. In various implementations, the device can include a symmetricoptical element with a first surface and a second surface intersected byan optical axis. The thickness of the device along the optical axis canvary between 0.5 mm and about 2.0 mm. The first and the second surfacescan be aspheric. In various implementations, the aspheric surfaces caninclude higher order aspheric terms.

In various implementations, the device can be configured as a piggybacklens that can be providing in addition to an existing lens that isconfigured to provide good foveal vision. The piggyback lens can besymmetric or asymmetric. The piggyback lens can be configured to beimplanted in the sulcus or in the capsular bag in front of the existinglens.

In various implementations, the device can be configured as a dual opticintraocular lens having a first lens and a second lens. One or bothsurfaces of the first and the second lens can be aspheric. In variousimplementations, one or both surfaces of the first and the second lenscan include higher order aspheric terms. In various implementations ofthe dual optic intraocular lens, the optic proximal to the closer to thecornea can have a high positive power and can be configured to be movedeither axially in response to ocular forces to provide accommodation. Invarious implementations of the device described herein, the refractivepower provided by optic can be changed in response to ocular forces. Thechange in the refractive power can be brought about through axialmovement or change in the shape of the optic. Various implementations ofthe device described herein can include a gradient index lens. One ormore surfaces of the optics included in various implementations of thedevice described herein can be diffractive to provide near vision. Theoptical zones of various implementations of the device described hereincan be split for different retinal eccentricities.

Another aspect of the subject matter disclosed herein includes a powercalculation diagnostic procedure that measures corneal topography, eyelength, retinal curvature, peripheral eye length, pupil position,capsular position, or any combination thereof in order to determinecharacteristic of the intraocular lens device that improves visualacuity and contrast sensitivity for patients with central visual fieldloss.

Implementations of intraocular devices described herein can include oneor more optics with a large optical zone. The implementations ofintraocular devices described herein are configured to focus obliquelyincident light in a location of the peripheral retina at an eccentricitybetween about 5-25 degrees (e.g., eccentricity of 10 degrees,eccentricity of 15 degrees, eccentricity of 20 degrees, etc.). Forpatient with a well-developed preferred retinal location (PRL), variousimplementations of the intraocular device can be configured to focusincident light at the PRL. For patients without a well-developed PRL,the implementations of intraocular device described herein can help inthe formation of the PRL. This disclosure also contemplates the use ofdiagnostic devices to determine a region of the peripheral retina whichprovides the best vision, determining the power of the intraoculardevice at various locations with the region of the peripheral retina anddetermining an intraocular device that would correct optical errorsincluding defocus, astigmatism, coma, spherical aberration, chromaticaberration (longitudinal and transverse) at the region of the peripheralretina. When determining the intraocular device that would correctoptical errors at the region of the peripheral retina, different figuresof merit can be used to characterize the optical performance ofdifferent configurations of the intraocular device and the intraoculardevice that provides the best performance can be selected. The differentfigures of merit can include MTF at spatial frequencies appropriate forthe retinal areas, weighting of retinal areas, neural weighting, andweighting of near vision function.

Another aspect of the subject matter described in this disclosure can beimplemented in an intraocular lens configured to improve vision for apatient's eye. The IOL comprises an optic comprising a first surface anda second surface opposite the first surface, the first surface and thesecond surface intersected by an optical axis. The optic is symmetricabout the optical axis. The first and the second surface of the opticare aspheric. The optic is configured to improve image quality of animage produced by light incident on the patient's eye at an obliqueangle with respect to the optical axis and focused at a peripheralretinal location disposed at a distance from the fovea. The imagequality is improved by reducing oblique astigmatism at the peripheralretinal location.

The image quality can also be improved by reducing coma at theperipheral retinal location. The oblique angle can be between about 1degree and about 25 degrees. The peripheral retinal location can bedisposed at an eccentricity of about 1 degree to about 25 degrees withrespect to the fovea in the horizontal or the vertical plane. Forexample, the peripheral retinal location can be disposed at aneccentricity between about 7 degrees and about 13 degrees in thehorizontal plane. As another example, the peripheral retinal locationcan be disposed at an eccentricity between about 1 degree and about 10degrees in the vertical plane. At least one of the surfaces of the firstor second viewing element can be aspheric. At least one of the surfacesof the first or second viewing element can be a toric surface, a higherorder aspheric surface, an aspheric Zernike surface or a Biconic Zernikesurface. An image formed by the IOL at the peripheral retinal locationcan have a modulation transfer function (MTF) of at least 0.2 (e.g., atleast 0.3, at least 0.4, at least 0.5. at least 0.6, at least 0.7, atleast 0.8, at least 0.9 or values there between) for a spatial frequencyof 30 cycles/mm for both the tangential and the sagittal foci. An imageformed by the IOL at the fovea can have a MTF of at least 0.2 (e.g., atleast 0.3, at least 0.4, at least 0.5. at least 0.6, at least 0.7, atleast 0.8, at least 0.9 or values there between) for a spatial frequencyof 100 cycles/mm for both the tangential and the sagittal foci.

The optic can be a meniscus lens with a vertex curving inwards fromedges of the optic. One of the first or second surface can includeredirecting elements. The redirecting elements can have a slope profileas described herein. The redirecting element can comprise one or morediffractive elements and/or one or more prismatic features. In variousimplementations, the optic can include diffractive features, prismaticfeatures, echelletes etc. to further improve the image quality at theperipheral retinal location. For example, the first and/or the secondviewing element can include diffractive features to provide increasesdepth of focus.

Another aspect of the subject matter described in this disclosure can beimplemented in a method of designing an intraocular lens (IOL)configured to be implanted in a patient's eye. The method comprisesdetermining a first surface profile of the optic and determining asecond surface profile of the optic. The determined surface profiles aresuch that the optic has an optical power that reduces optical errors inan image produced at a peripheral retinal location disposed at adistance from the fovea, wherein the image is produced by focusing lightincident on the patient's eye at an oblique angle with respect to anoptical axis intersecting the patient's eye at the peripheral retinallocation. The first surface profile and the second surface profile canbe aspheric.

The optical power of the IOL that reduces optical errors at theperipheral retinal location can be obtained from a measurement of anaxial length along an axis which deviates from the optical axis andintersects the retina at the peripheral retinal location. The opticalpower of the IOL that reduces optical errors at the peripheral retinallocation can be obtained from an estimate of an axial length along anaxis which deviates from the optical axis and intersects the retina atthe peripheral retinal location, the estimate based on measured ocularcharacteristics of the patient obtained using a diagnostic instrument.The measured ocular characteristics can include axial length along theoptical axis, corneal power based at least in part on measurements oftopography of the cornea, pre-operative refractive power and otherparameters. The image produced at the peripheral retinal location canhave reduced peripheral astigmatism and/or coma.

Another aspect of the subject matter disclosed herein can be implementedin a method of selecting an intraocular lens (IOL) configured to beimplanted in a patient's eye. The method comprises obtaining at leastone characteristic of the patient's eye using a diagnostic instrument;and selecting an IOL having an optical power that reduces optical errorsin an image produced at a peripheral retinal location of the patient'seye disposed at a distance from the fovea, wherein the IOL is configuredto produce an image by focusing light incident on the patient's eye atan oblique angle with respect to an optical axis intersecting thepatient's eye at the peripheral retinal location. The optical power ofthe IOL is obtained and/or optimized based on the obtainedcharacteristic. A first surface of the IOL can be aspheric. The IOL canbe symmetric about the optical axis. A second surface of the IOL can beaspheric. The image can have reduced coma and/or astigmatism. Theoblique angle can be between about 1 degree and about 25 degrees. TheIOL can be configured such that the image has a modulation transferfunction (MTF) of at least 0.3 for a spatial frequency of 30 cycles/mmfor both tangential and sagittal foci. The IOL can be configured toprovide at least 0.5 Diopter of astigmatic correction at the peripheralretinal location

The obtained characteristic can include at least one of axial lengthalong the optical axis of the patient's eye, corneal power based atleast in part on measurements of topography of the cornea, an axiallength along an axis which deviates from the optical axis and intersectsthe retina at the peripheral retinal location, a shape of the retina ora measurement of optical errors at the peripheral retinal location. Insome implementations, the optical power can be obtained from an estimateof an axial length along an axis which deviates from the optical axisand intersects the retina at the peripheral retinal location. Theestimate can be based on the axial length along the optical axis of thepatient's eye and corneal power.

At least one of the surfaces of the first viewing element or the secondviewing element can include a redirecting element. The redirectingelement can have a tailored slope profile as discussed herein. Theredirecting element can include a diffractive feature and/or a prismaticfeature.

The methods and systems disclosed herein can also be used to customizeIOLs based on the geometry of a patient's retina, the extent of retinaldegeneration and the geometry and condition of other structures in thepatient's eye. Various embodiments described herein can also treat otherconditions of the eye such as cataract and correct for presbyopia,myopia and/or astigmatism in addition to improving visual acuity and/orcontrast sensitivity of peripheral vision.

The methods and systems described herein to deflect incident light awayfrom the fovea to a preferred retinal location (PRL) can also be appliedto spectacle lenses, contact lenses, or ablation patterns for lasersurgeries (e.g., LASIK procedures).

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

BRIEF DESCRIPTION OF THE DRAWINGS

Example implementations disclosed herein are illustrated in theaccompanying schematic drawings, which are for illustrative purposesonly.

FIG. 1 is a diagram illustrating the relevant structures and distancesof the human eye.

FIG. 2 illustrates different regions of the retina around the fovea.

FIGS. 3A-3K illustrate simulated vision with a central scotoma alongwith ophthalmic device embodiments. A ray diagram lies to the right ofeach simulation.

FIG. 4A-1 is a diagram of an eye implanted with an intraocular lens thatdeflects incident light to a preferred retinal location (PRL). FIG. 4A-2is a ray trace illustrating rays originating from the posterior surfaceof a lens. FIG. 4B illustrates an image obtained by a PRL diagnosticdevice.

FIG. 5A illustrates an implementation of an optic including at least oneaspheric surface that can improve the visual outcome for a patient withAMD.

FIG. 5B illustrates the surface profile of the aspheric surface of thelens illustrated in FIG. 5A in a first meridian. FIG. 5C illustrates thesurface profile of the aspheric surface of the lens illustrated in FIG.5A in a second meridian.

FIG. 5D shows a cross-section view of an eye with a central scotoma atthe fovea and implanted with an implementation of an IOL including theoptic illustrated in FIG. 5A. FIG. 5D-1 and FIG. 5D-2 illustrate regionsof peripheral retina where the optic illustrated in FIG. 5A can improveimage quality. FIG. 5D-3 shows the area around a preferred retinallocation (PRL) towards which incident light from the off-axis object isdirected by the IOL 500. FIG. 5E graphically illustrates the variationin image quality versus eccentricity for an implementation of an opticconfigured to improve image quality at a peripheral retinal location andan optic configured to improve image quality at the fovea. FIG. 5F showsa perspective view of the IOL 500 and the optical rays incident on theIOL from an off-axis object.

FIG. 6A shows the modulation transfer function for a standard toric IOLthat provides good foveal vision at an eccentricity of 10 degrees. FIG.6B shows the modulation transfer function provided by an enhanced toricIOL with astigmatic correction at an eccentricity of 10 degrees. FIG. 6Cshows the modulation transfer function provided by the optic illustratedin FIG. 5A at an eccentricity of 10 degrees. FIG. 6D shows themodulation transfer function provided by the enhanced toric IOL at thefovea. FIG. 6E shows the modulation transfer function provided by theoptic illustrated in FIG. 5A at the fovea.

FIG. 7A shows a cross-section view of an embodiment of a standardintraocular lens (IOL) configured to provide improved vision at alocation of the peripheral retina.

FIG. 7B shows a cross-section view of an embodiment of an enhanced toricIOL configured to provide improved vision at a location of theperipheral retina.

FIG. 7C shows a cross-section view of an embodiment of a symmetricsingle optic IOL configured to provide improved vision at a location ofthe peripheral retina.

FIG. 7D shows a cross-section view of an embodiment of an asymmetricsingle optic IOL configured to provide improved vision at a location ofthe peripheral retina.

FIG. 7E shows a cross-section view of an embodiment of a thick symmetricIOL configured to provide improved vision at a location of theperipheral retina.

FIG. 7F shows a cross-section view of an embodiment of a moved symmetricIOL configured to provide improved vision at a location of theperipheral retina.

FIG. 7G shows a cross-section view of an embodiment of a movedasymmetric IOL configured to provide improved vision at a location ofthe peripheral retina.

FIG. 7H shows a cross-section view of an embodiment of a dual optic IOLconfigured to provide improved vision at a location of the peripheralretina.

FIG. 7I shows a cross-section view of an embodiment of a dual optic IOLconfigured to provide improved vision at a location of the peripheralretina and at the fovea.

FIG. 7J shows a cross-section view of an embodiment of an accommodatingdual optic IOL configured to provide improved vision at a location ofthe peripheral retina.

FIG. 7K shows a cross-section view of an embodiment of an accommodatingdual optic IOL configured to provide improved vision at a location ofthe peripheral retina and at the fovea.

FIG. 7L shows a cross-section view of an embodiment of a symmetricpiggyback IOL configured to provide improved vision at a location of theperipheral retina and at the fovea.

FIG. 7M shows a cross-section view of an embodiment of an asymmetricpiggyback IOL configured to provide improved vision at a location of theperipheral retina and at the fovea.

FIG. 8 illustrates an example intraocular lens having two zones.

FIG. 9 illustrates an example intraocular lens having two zones withdifferent optical powers and different deflection angles.

FIG. 10 illustrates an example method for providing an intraocular lenswith two or more zones to improve overall vision where there is a lossof central vision.

FIG. 11 illustrates a plot and a zoomed-in version of the plot showingray convergence and image focus at a PRL when redirecting incident lightusing a simple prism.

FIG. 12 illustrates a plot and a zoomed-in version of the plot showingray convergence and image focus at a PRL when redirecting incident lightusing a flat Fresnel prism.

FIGS. 13-15 illustrate slope profiles of posterior surfaces of exampleintraocular lenses, the slope profiles based on analytical computations.

FIG. 16 illustrates a slope profile of a posterior surface of an exampleintraocular lens and a slope profile of a redirection element includinga plurality of zones of constant slope, the slope in each zone based onanalytical computations.

FIG. 17 illustrates a plot and a zoomed-in version of the plot showingray convergence and image focus at a PRL when redirecting incident lightusing the redirection element of FIG. 16.

FIG. 18 illustrates a plot and a zoomed-in version of the plot showingray convergence and image focus at a PRL when redirecting incident lightusing a tailored redirection element having an iteratively tuned slopeprofile.

FIG. 19 illustrates a plot and a zoomed-in version of the plot showingray convergence and image focus at a PRL when redirecting incident lightusing a Fresnel prism having an increased thickness and fewer Fresnelzones, a redirection element including zones of constant slope, theslope profiles based on analytical computations.

FIG. 20 illustrates a plot and a zoomed-in version of the plot showingray convergence and image focus at a PRL when redirecting incident lightusing a redirection element having an increased thickness and fewerFresnel zones, the redirection element having an iteratively tuned slopeprofile.

FIG. 21 illustrates an example method for providing an intraocular lensto focus images onto a peripheral retina locus.

FIG. 22 illustrates an example of an asymmetric refractive index profilefor an optical component that can be included in an ophthalmic devicethat is capable of deflecting light away from the fovea to the PRL.

FIG. 23 illustrates an embodiment of an ophthalmic device including anoptical component with a gradient refractive index (GRIN) profile.

FIG. 24 shows the optical output from the ophthalmic device depicted inFIG. 19.

FIG. 25 illustrates an example implementation of a linear grating.

FIG. 26 illustrates an embodiment of an ophthalmic device including anembodiment of a diffraction grating.

FIG. 27 shows the optical output from an embodiment of an ophthalmicdevice including a polychromatic diffraction grating.

FIG. 28 shows the optical output from an embodiment of an ophthalmicdevice including a polychromatic diffraction grating and an achromaticoptical component.

FIG. 29 illustrates a block diagram of an example IOL design system fordetermining properties of an intraocular lens configured to improveoverall vision where there is a loss of central vision.

FIG. 30 illustrates parameters used to determine an optical power of anIOL based at least in part on a location of a PRL in a patient.

FIG. 31A and FIG. 31B illustrate implementations of a method fordetermining an optical power of an IOL tailored to improve peripheralvision.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

It is to be understood that the figures and descriptions have beensimplified to illustrate elements that are relevant for a clearunderstanding of embodiments described herein, while eliminating, forthe purpose of clarity, many other elements found in typical lenses,lens systems and lens design methods. Those of ordinary skill in thearts can recognize that other elements and/or steps are desirable andmay be used in implementing the embodiments described herein.

The terms “power” or “optical power” are used herein to indicate theability of a lens, an optic, an optical surface, or at least a portionof an optical surface, to focus incident light for the purpose offorming a real or virtual focal point. Optical power may result fromreflection, refraction, diffraction, or some combination thereof and isgenerally expressed in units of Diopters. One of ordinary skill in theart will appreciate that the optical power of a surface, lens, or opticis generally equal to the refractive index of the medium (n) of themedium that surrounds the surface, lens, or optic divided by the focallength of the surface, lens, or optic, when the focal length isexpressed in units of meters.

The angular ranges that are provided for eccentricity of the peripheralretinal location in this disclosure refer to the visual field angle inobject space between an object with a corresponding retinal image on thefovea and an object with a corresponding retinal image on a peripheralretinal location.

FIG. 1 is a schematic drawing of a human eye 200. Light enters the eyefrom the left of FIG. 1, and passes through the cornea 210, the anteriorchamber 220, a pupil defined by the iris 230, and enters lens 240. Afterpassing through the lens 240, light passes through the vitreous chamber250, and strikes the retina, which detects the light and converts it toa signal transmitted through the optic nerve to the brain (not shown).The eye 200 is intersected by an optical axis 280. The cornea 210 hascorneal thickness (CT), which is the distance between the anterior andposterior surfaces of the center of the cornea 210. The corneal centerof curvature 275 can coincide with geometric center of the eye 200. Theanterior chamber 220 has an anterior chamber depth (ACD), which is thedistance between the posterior surface of the cornea 210 and theanterior surface of the lens 240. The lens 240 has lens thickness (LT)which is the distance between the anterior and posterior surfaces of thelens 240. The eye has an axial length (AXL) which is the distancebetween the center of the anterior surface of the cornea 210 and thefovea 260 of the retina, where the image is focused. The LT and AXL varyin eyes with normal accommodation depending on whether the eye isfocused on near or far objects.

The anterior chamber 220 is filled with aqueous humor, and opticallycommunicates through the lens 240 with the vitreous chamber 250. Thevitreous chamber 250 is filled with vitreous humor and occupies thelargest volume in the eye. The average adult eye has an ACD of about3.15 mm, although the ACD typically shallows by about 0.01 mm per year.Further, the ACD is dependent on the accommodative state of the lens,i.e., whether the lens 240 is focusing on an object that is near or far.

FIG. 2 illustrates different regions of the retina around the fovea 260.The retina includes a macular region 207. The macular region 207 has twoareas: central and peripheral. Light focused on the central areacontributes to central vision and light focused on the peripheral areacontributes to peripheral vision. The central region is used to viewobjects with higher visual acuity, and the peripheral region is used forviewing large objects and for capturing information about objects andactivities in the periphery, which are useful for activities involvingmotion and detection.

The macular region 207 is approximately 5.5 mm in diameter. The centerof the macular region 207 is approximately 3.5 mm lateral to the edge ofthe optic disc 205 and approximately 1 mm inferior to the center of theoptic disc 205. The shallow depression in the center of the macularegion 207 is the fovea 260. The fovea 260 has a horizontal dimension(diameter) of approximately 1.5 mm. The curved wall of the depressiongradually slopes to the floor which is referred to as the foveola 262.The diameter of the foveola 262 is approximately 0.35 mm. The annularzone surrounding the fovea 260 can be divided into an inner parafovealarea 264 and an outer perifoveal area 266. The width of the parafovealarea 264 is 0.5 mm and of the perifoveal area 266 is 1.5 mm.

For the general population incident light is focused on the fovea 260.However, in patients suffering from AMD, a scotoma develops in thefoveal region which leads to a loss in central vision. Such patientsrely on the region of the peripheral retina around the fovea (e.g., themacular region 207) to view objects. For example, patients with AMD canfocus incident light on the PRL either by using a magnifying lens thatenlarges the image formed on the retina such that a portion of the imageoverlaps with a portion of the peripheral retina around the fovea or byrotating the eye or the head, thus using eccentric fixation such thatlight from the object incident at oblique angles is focused on a portionof the peripheral retina around the fovea. The visual outcome forpatients suffering from AMD can be improved if optical refractive errorsresulting from oblique incidence of light or coma were corrected. Insome AMD patients, a portion of the peripheral retina around the foveamay have has greater visual acuity and contrast sensitivity compared toother portions of the peripheral retina. This portion is referred to asthe preferred retinal location (PRL). The visual outcome for suchpatients may be improved if incident light were focused at the PRL andthe ophthalmic solutions corrected for optical refractive errors at thePRL. This is explained in detail below.

Consider a patient suffering from AMD who desires to view a smart phoneat a normal distance (23 cm simulated here). In such a patient, thescotoma will block out the view as seen in FIG. 3A. One solution toimprove the visual outcome is to bring the object of interest closer tothe eye. This requires a magnifying glass to place the object opticallyat infinity. FIG. 3B illustrates the simulated view of a smart phoneviewed with the aid of a magnifying glass by a patient with a centralscotoma. The effect of the magnifying glass is to reduce the objectdistance and enlarge the size of the image formed on the retina suchthat it overlaps with a portion of the peripheral retina around thefovea. For the purpose of simulations, it is assumed that the magnifyingglass is used and hence the phone is assumed to be at a distance of 7.5cm. If the patient has cataract in addition to AMD and is implanted witha standard IOL, the peripheral errors will increase. FIG. 3C shows thesimulated view of a smart phone viewed by a patient implanted with astandard IOL and who also suffers from AMD. A comparison of FIGS. 3B and3C illustrates that the smart phone screen appears more blurry whenviewed by a patient implanted with a standard IOL due to the increase inperipheral errors.

Another solution to improve visual outcome is to utilize eccentricfixation to focus light from a visual interest on to a portion of theperipheral retina. FIG. 3D illustrates a simulated view of a smart phoneviewed using eccentric fixation to focus light from the smart phonescreen to a position on the peripheral retina located about 12.5 degreesaway from the fovea. Since, the image formed at the position on theperipheral retina is formed by light that is obliquely incident,refractive errors arising from the oblique incidence of light maydegrade the visual quality. Accordingly, ophthalmic solutions that cancorrect optical refractive errors arising from oblique incidence oflight may benefit AMD patients who rely on eccentric fixation to viewobjects.

By selecting an IOL with appropriate refractive properties, the imagequality at a peripheral retinal location can be improved. For example,the IOL in FIG. 3E is selected to correct about 2.5 D of astigmatism andabout 0.7 D of sphere. A comparison of FIGS. 3E and 3D shows that thesimulated image in FIG. 3E is less blurry than the simulated image inFIG. 3D.

To increase contrast sensitivity in different portions of the retinaincluding the PRL, it may be advantageous to increase the depth offield. It is found that if large amounts of aberrations, e.g. greaterthan about 0.5 μm of spherical aberration for a 5 mm pupil, are imposed,the eye becomes more tolerant to the refractive errors, at the slightcost of image quality at the PRL. This is illustrated in FIG. 3F.

Another method to increase contrast sensitivity in different portions ofthe retina including the PRL includes providing multi-refraction for thearea surrounding the PRL. In many cases, due to the symmetry of the eye,it can be sufficient to provide two refraction zones: one for thehorizontal field and one for the vertical field. Each refractive zonecan be symmetrically disposed around the fovea. For example, onerefractive zone can be disposed about a location that is at an angle ofabout 12.5 degrees with respect to an optical axis 2501 intersecting thecornea and the retina and passing through the fovea. In variousimplementations, the two refractive zones can be disposed asymmetricallywith respect to the optical axis 2501. Together, the two refractivezones can create a circle of good vision around the scotoma, asillustrated in FIG. 3G. The area between the two circles 2505 and 2510represents the area of increased contrast sensitivity in FIG. 3G.

Based on this, an IOL configured for reading can create a continuous orpiece-wise continuous linear refractive region disposed above or belowthe scotoma. The linear refractive region can include multiplerefractive zones. FIG. 3H illustrates an implementation of a linearrefractive region including three refractive zones 2515, 2520 and 2535created by an IOL that is configured for reading.

The implementation of the IOL illustrated in FIG. 3H relies on eccentricfixation to move the visual field of interest above or below thescotoma. However, some patients may not desire to use eccentricfixation. For such patients, an IOL configured for reading can provide alinear refraction region on both sides of the scotoma. In variousimplementations, an IOL providing a linear refraction region on bothsides of the scotoma can be accomplished just a single refractivecorrection, due to the symmetry of the peripheral errors, as shown inFIG. 3I.

So far, it has been assumed that the patient wears a magnifying aid whenlooking at close objects (a single strong lens, also called a loupe).However, all the implementations mentioned above can be configured toprovide good vision even without the aid of a magnifying element. Allthe implementations discussed above can be combined with a multifocalapproach, where part of the IOL is powered for a far distance, andanother part is powered for a very close distance, as shown in FIG. 3J.Furthermore, all the implementations mentioned above can also becombined with the redirection solution, described in here with referenceto FIGS. 8-28. For example, FIG. 3K illustrates an implementation of anIOL that includes a redirection element such that light incident along adirection that is substantially parallel to the optical axis of the eyeis focused at a PRL. In such implementations, the patient does not haveto rely on eccentric fixation to have increased contrast sensitivity.

As discussed above, some patient may have a well-developed PRL and mayprefer focusing incident light on the PRL. Such patients can benefitfrom an IOL that can focus light at the PRL instead of the fovea. FIG.4A-1 is a diagram of the eye 200 implanted with an IOL 295 that deflectsincident light away from the fovea 260 to the PRL 290. FIG. 4A-2 is aray trace illustrating rays originating from the posterior surface 285of a lens, such as, for example, the natural lens 240 or an intraocularlens configured to provide good foveal vision. The lens is configuredsuch that the rays originating from the posterior surface 285 of thelens are focused on the fovea 260. Patients suffering from AMD sufferfrom central vision loss and rely on peripheral vision to accomplishtheir daily tasks. Usually, in such patients a portion 290 of theperipheral area of the macular regions 207 has greater acuity andcontrast sensitivity compared to other portions of the peripheral area.The portion 290 of the peripheral area of the macular regions 207 thathas greater acuity and contrast sensitivity compared to other portionsof the peripheral area is referred to as the preferred retinal location(PRL). Since, patients with AMD are not able to perceive images producedby light focused at the fovea 260, it is advantageous if incident lightis deflected away from the fovea 260 to the PRL 290. Accordingly, suchpatients can benefit from an IOL that can focus light at the PRL 290instead of the fovea 260.

For most patients, the PRL 290 is at a distance less than or equal toabout 3.0 mm from the fovea 260. Accordingly, the IOL 295 can beconfigured to deflect incident light by an angle between about 3.0degrees and up to about 30 degrees such that it is focused at apreferred location within a region at a distance of about 3.0 mm aroundthe fovea 260. The IOL 295 can be customized for a patient bydetermining the PRL for each patient and then configuring the IOL 295 todeflect incident light such that it is focused at the PRL. The method tofind the PRL of any patient is based on perimetry. One perimetry methodto locate the PRL is Goldmann Perimetry. The perimetry method to locatethe PRL includes measuring the visual field of a patient. For example,the patient can be asked to fixate on a cross and flashes of lights arepresented at various parts in the field and the responses are recorded.From the recorded responses, a map of how sensitive the peripheralretina is can be created. The patient can be trained to consistently usethe healthy and more sensitive portions of the retina. The perimetrymethod can be further enhanced by microperimetry, as used by e.g. theMacular Integrity Assessment (MAIA) device, where the retina is trackedin order to place the stimuli consistently and eye movement areaccounted for.

The PRL can also be located subjectively, by asking the patient tofixate as they want into an OCT-SLO instrument. The instrument canobtain one or more images of the retina and determining which portionsof retina are used more than the other. One method of determining theportions of retina that are used more includes imposing the parts offixation onto an image of the retina. The OCT-SILO instrument can alsobe used to obtain normal images of the retina. FIG. 4B illustrates animage obtained using the perimetry method and the fixation method. FIG.4B shows a photo of the retina with a central scotoma 415. Thered-yellow-orange dots in the region marked 405 are the results of theperimetry. Perimetry results indicate that spots closer to the scotoma415 perform worse that spots farther away from the scotoma 415. The manysmall teal dots in the region marked 410 are the fixation points, andthe lighter teal point 420 is the average of the dots in the region 410.Based on the measurements, the PRL can be located at either point 420 orone some of the yellow points 425 a-425 d. Accordingly, an IOL 295 canbe configured to focus an image at one of the points 420 or 425 a-425 d.The determination of the PRL for a patient having both cataract and AMDcan be made by methods other than the methods described above.

Since, AMD patients rely on their peripheral vision to view objects,their quality of vision can be improved if optical errors in theperipheral vision are identified and corrected. Optical powercalculation for an IOL configured for foveal vision is based onmeasuring eye length and corneal power. However, power calculation foran IOL that focuses objects in an area of the peripheral retina aroundthe fovea can depend on the curvature of the retina as well as theoblique astigmatism and coma that is associated with the obliqueincidence of light in addition to the eye length and the corneal power.

Methods that are used by an optometrist to measure optical power forspectacle lenses or contact lenses for non AMD patients with good fovealvision are not practical for measuring optical power for ophthalmicsolutions (e.g., IOL, spectacle lenses, contact lenses) for peripheralvision. Optometrists use various machines such as autorefractors, aswell as a method called subjective refraction wherein the patient readslines on the wall chart. The response is then used to gauge which triallenses to put in, and the lenses that give the best results are used.However, such a method is not practical to determine which ophthalmicsolution is best for a patient with AMD who relies on peripheral visionto view objects since, the performance estimates are rendered unreliableby the phenomenon of aliasing (a phenomenon which makes striped shirtslook wavy on some television sets with poor resolution), the difficultyof fixation and general fatigue associated with orienting the head/eyeto focus objects on the peripheral retina. Instead, the methods used toevaluate the optical power of ophthalmic solutions for AMD patients relyon peripheral wavefront sensors to estimate peripheral optical errors.Peripheral wavefront sensors illuminate a small patch of the PRL usinglasers and evaluate how the light reflected and coming out of the eye isshaped through an array of micro-lenses. For example, if the lightcoming out of the eye is converging, the patient is myopic at the PRL.

In various patients suffering from AMD as well as cataract, the naturallens 240 can be removed and replaced with the IOL 295, or implanted inthe eye 200 in addition to another IOL placed previously or at the sametime as the IOL 295. In some patients suffering from AMD, the IOL 295can be implanted in the eye 200 in addition to the natural lens 240. InFIG. 4A-1, the IOL 295 is implanted in the capsular bag. Where possible,the IOL 295 is placed as close to the retina as possible. However, inother implementations, the IOL 295 can be implanted within the capsularbag in front of another IOL or in front of the capsular bag. Forexample, the IOL 295 can be configured as an iris, sulcus or anteriorchamber implant or a corneal implant. By selecting an IOL 295 withappropriate refractive properties, the image quality at the PRL 290 canbe improved.

The visual outcome at the PRL is poor as compared to the foveal visualdue to a decreased density of ganglion cells at the PRL and/or opticalerrors and artifacts that arise due to oblique incidence of light (e.g.,oblique astigmatism and coma). As discussed above, patients with AMD canreceive substantial improvement in their vision when refractive errorsat the PRL are corrected. Many of the existing embodiments of IOLs thatare configured to improve visual outcome for a patient are notconfigured to correct for refractive errors in the image generated atthe PRL.

Various embodiments of the IOLs disclosed herein are configured to focuslight at a location on the peripheral retina to produce good qualityimages, for example, images produced at the location on the peripheralretina can have a quality that is substantially similar to the qualityof images produced at the fovea. The images produced at the location onthe peripheral retina by the IOLs disclosed herein can have reducedartifacts from optical effects such as oblique astigmatism, coma orother higher order aberrations. Other embodiments are based on the factthat the location on the peripheral retina is not used in the same wayas the fovea. For example, it may be harder to maintain fixation on thePRL, so it may be advantageous to increase the area of the retina whereincident light is focused by the IOL in order to have sufficient visualacuity and/or contrast sensitivity even when fixation is not maintainedand/or when the eye is moved linearly as in during reading. As such, theretinal area of interest can cover areas where the refraction differssubstantially due to differences e.g. in retinal curvature and obliqueastigmatism. Various embodiments of IOLs described herein can be used todirect and/or focus light entering the eye along different directions atdifferent locations of the retina. Simulation results and ray diagramsare used to describe the image forming capabilities of the embodimentsdescribed herein. To simulate the images formed by various embodimentsof IOLs described herein, it is assumed that a central scotoma resultsin a blackened out middle area and that the rest of the image quality isdegraded by average amounts of peripheral refractive errors, astigmatismand coma. Additionally, the limitations imposed by ganglion cells aresimulated. Any combination of multi-refraction correction is simulatedas well.

As used herein, an IOL refers to an optical component that is implantedinto the eye of a patient. The IOL comprises an optic, or clear portion,for focusing light, and may also include one or more haptics that areattached to the optic and serve to position the optic in the eye betweenthe pupil and the retina along an optical axis. In variousimplementations, the haptic can couple the optic to zonular fibers ofthe eye. The optic has an anterior surface and a posterior surface, eachof which can have a particular shape that contributes to the refractiveproperties of the IOL. The optic can be characterized by a shape factorthat depends on the radius of curvature of the anterior and posteriorsurfaces and the refractive index of the material of the optic. Theoptic can include cylindrical, aspheric, toric, or surfaces with a slopeprofile configured to redirect light away from the optical axis and/or atight focus.

It is envisioned that the solution herein can be applied to anyeccentricity. For example, in some patients, a location that is disposedat a small angle from the fovea can be used as the PRL while in someother patients, a location that is disposed at an angle of about 30degrees from the fovea can be used as the PRL. This is further explainedbelow with reference to FIG. 5D which shows a cross-section view of aneye with a central scotoma at the fovea 260 and implanted with animplementation of an IOL 500. The IOL 500 can including an optic have ananterior surface configured to receive incident light from an object 516and a posterior surface configured to redirect light out of the IOLtowards a preferred retinal location (PRL) 520 on the retina. Asdiscussed above the PRL 520 can be disposed at an angle with respect toan optical axis 280 of the eye. In various implementations, the angle θthat the PRL 2610 makes with the optical axis 280 can vary between asmall angle (e.g., 2-5 degrees) and about 45-60 degrees.

Additionally, various implementations of optics disclosed herein thatare configured to improve contrast sensitivity at the PRL can becombined with a diagnostics system that identifies the best potentialPRL after correction of refractive errors. Normally, optical errors canrestrict the patient from employing the best PRL, making them preferneurally worse but optically better region. Since variousimplementations of optics disclosed herein can correct optical errors atthe PRL, it may be advantageous to find the best PRL for the patientwith a method that is not degraded by optical errors (e.g. adaptiveoptics). Various implementations of optics disclosed herein can bedesigned by taking advantage of the symmetries that exists with regardsto peripheral refractive errors in many patients.

Symmetric Lens to Generate an Image at a Location of the PeripheralRetina for AMD Patients

Patients with AMD who do not have a well-developed PRL could potentiallybe provided with a symmetric lens that is configured to focus lightincident at different oblique angles with respect to the optical axis280 of the eye of the patient to their corresponding location of theperipheral retina. The lens can be symmetric about an optical axis ofthe lens such that the image quality in a region around the optical axisis uniform. The lens could also be configured to correct errorsresulting from oblique incidence of light such as oblique astigmatismand/or peripheral coma for every direction.

FIG. 5A illustrates an implementation of an optic 500 that that isconfigured to focus light incident at oblique angles with respect to theoptical axis 280 of the eye of the patient at a location of theperipheral retina. The optic 500 has a first surface 505 and a secondsurface 510. An optical axis 515 passes through the geometric center ofthe optic 500 and joins the center of curvatures of the first and secondsurfaces. The optic 500 illustrated in FIG. 5A is symmetric about theoptical axis 515 such that the image quality in a region around theoptical axis is uniform. This disclosure also includes implementationsof an optic that can be configured to be asymmetric about an opticalaxis of the optic 500 such that the image quality in a particularlocation with respect to the optical axis is better than the imagequality at a different location.

The optic 500 can be included in an intraocular lens (IOL) that can beimplanted in the eye of a patient. For example, the optic 500 can beincluded in an IOL that is configured to be inserted between thepupil/iris of the patient and the capsular bag (e.g., in the sulcus ofthe eye). As another example, the optic 500 can be included in an IOLthat is configured to be implanted in the capsular bag of the patient'seye. The IOL including the optic 500 can be implanted in the patient'seye such that the optical axis 515 of the optic 500 is coincident withthe optical axis 280 of the patient's eye. The IOL including the optic500 can be implanted in the patient's eye such that the optical axis 515of the optic 500 is offset and/or tilted with respect to the opticalaxis 280 of the patient's eye. When implanted, the first surface 505 canface the cornea of the patient's eye and the second surface 510 can facethe retina. Accordingly, in various implementations, the first surface505 can be referred to as the anterior surface and the second surface510 can be referred to as the posterior surface. Alternately, whenimplanted the first surface 505 can face the retina of the patient's eyeand the second surface 510 can face the cornea. The thickness of theoptic 500 along the optical axis 515 can be less than 1.5 mm. Forexample, the thickness of the optic along the optical axis can varybetween about 0.25 mm and about 0.4 mm, about 0.3 mm and about 0.5 mm,about 0.4 mm and about 0.6 mm, about 0.5 mm and about 0.7 mm, about 0.6mm and about 0.8 mm, about 0.7 mm and about 0.9 mm, 0.9 mm and about 1.0mm, about 0.95 mm and about 1.25 mm, about 1.2 mm and about 1.5 mm orvalues therebetween.

The first surface 505 and/or the second surface 510 can be spheric,aspheric, conic, etc. The first surface 505 and/or the second surface510 can be described mathematically by a polynomial function in eitherCartesian or polar coordinates. For example, the first surface 505and/or the second surface 510 can be described mathematically byequation (1) below:

$\begin{matrix}{z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {\sum\limits_{i = 1}^{6}{\alpha_{i}r^{2\; i}}}}} & (1)\end{matrix}$

where z is the sag of the surface, c is the curvature of the surface, rthe radial distance from the optical axis 515, k the conic constant andα₁, α₂, α₃, α₄, α₅, and α₆, the aspheric coefficients. Without any lossof generality, the curvature of the surface can be correlated to theinverse of the radius of curvature R. The surface described by equation(1) above is symmetric about the optical axis and thus does not have anyangular dependency. Accordingly, the optical effect (and/or imagequality) is independent of angular location.

When the aspheric coefficients are zero, the first surface 505 and/orthe second surface 510 can be considered to be a conic. Since each ofthe first surface 505 and the second surface 510 surface can bedescribed by eight (8) parameters including the curvature c, the conicconstant k and the six aspheric coefficients α₁, α₂, α₃, α₄, α₅, and α₆,fourteen (14) degrees of freedom are available when designing the lens.This allows sufficient flexibility to achieve correction of peripheraloptical errors at any location on the peripheral retina including aspecific location on the peripheral retina (e.g., the PRL).

The values of the surface parameters such as radius of curvature,aspheric coefficients, conic constant, etc. can be different for thefirst surface 505 and the second surface 510 of the optic 500 can bedifferent. For example, the surface that faces the cornea can have ahigh conic constant (e.g., between 10 and 1000) and the surface thatfaces the retina can have a low conic constant (e.g., between 0 and 10).The curvature of the posterior surface of the optic 500 that faces theretina can be higher than the curvature of the anterior surface thatfaces the cornea. For example, the anterior surface can be flat or closeto flat in some implementations. Accordingly, the optic 500 can have ameniscus shape such that vertex of the optic 500 is curved inwards fromthe edge of the optic 500.

In various implementations, the radius of curvature of the first and thesecond surface of the optic 500 be between about—4 mm and flat. Theconic constant of the first and the second surface of the optic 500 canhave a value between 0 and 1000. The aspheric coefficient α₁ can have avalue between about −10E-03 and 10E-03. The aspheric coefficient α₂ canhave a value between about −5E-03 and 5E-03. The aspheric coefficient α₃can have a value between about −10E-04 and about 10E-04. The asphericcoefficient α₄ can have a value between about −10E-05 and about 10E-05.The aspheric coefficient α₅ can have a value between about −5E-05 andabout 5E-05. The aspheric coefficient α₆ can have a value between about−10E-07 and about 10E-07.

One method of determining the first surface 505 and the second surface510 of the optic 500 includes selecting values for the six parametersthat describe the first surface 505 and the second surface 510 thatreduces or minimizes one or more optical errors (or increases ormaximizes one or more figures of merit) at a desired location of theperipheral retinal for one or more angles of incidence. Since, theavailable degrees of freedom are large (e.g., 12 or 14), it is possiblethat a local minima for the optical errors is achieved by the determinedsurface profile instead of the absolute minima. Thus, the determinedsurface may not be the optimal surface. The process of determining thesurface profile that provides the most reduction in optical errors at adesired location of the peripheral retinal for one or more angles ofincidence can be improved by choosing appropriate starting values forthe different parameters and an appropriate figure of merit tocharacterize the optical performance. Some possible figures of meritthat effectively characterize the optical performance of the optic forpatients with AMD can include modulus of the optical transfer function(MTF). The MTF for the optic 500 can be calculated for both sagittalrays and tangential rays originating from an object disposed withrespect to the intersection of the optic and the optical axis of theeye. Accordingly, two MTF curves are calculated one for sagittal raysand the other for tangential rays. For an image to have good quality andsufficient contrast sensitivity, the MTF for both the tangential raysand the sagittal rays should be above a threshold. The MTF is calculatedfor various off-axis positions of the object represented by coordinatesalong the x-direction and the y-direction in a Cartesian coordinatesystem in which the point of intersection of the optic and the opticalaxis of the eye is disposed at the origin of the Cartesian coordinatesystem and the optical axis is along the z-direction. In variousimplementations, the point of intersection of the optic and the opticalaxis of the eye can coincide with the geometric of the optic and/or thegeometric center of a surface of the optic.

The MTF of the optic refers to how much of the contrast ratio in theobject is preserved when the object is imaged by the optic. A MTF valueof 1.0 indicates that the optic does not degrade the contrast ratio ofthe object and a MTF value of 0 indicates that the contrast ratio isdegraded such that adjacent lines in the object cannot be resolved whenthe object is imaged by the optic. Accordingly, MTF is a measure ofcontrast sensitivity or sharpness. Another figure of merit can includeaverage MTF for a range of retinal locations and eccentricities, eitherclose to a single PRL or for multiple PRLs for the patient, and withspatial frequencies chosen to match the retinal sampling. Other figuresof merit can include area under the MTF curve for different spatialfrequencies, average MTF for a range of spatial frequencies orcombinations of the figures of merit listed here.

Appropriate starting values of curvature include values of curvaturethat provide increased on-axis refractive correction. Appropriatestarting values of aspheric coefficients α₁, α₂, α₃, α₄, α₅, and α₆ canbe chosen from Seidel theory so as to minimize (or substantially reduce)oblique astigmatism and coma through interaction with the distancebetween IOL and pupil.

One method of determining the optic that provides the best performanceat a desired location of the peripheral retinal for one or more anglesof incidence can include starting from an optic that is meniscus shapedand then optimizing the different parameters described above for the twosurfaces to improve one or more figures of merit (e.g., improve theperipheral MTF). The optimization process can be done on an electronicprocessor (e.g., a computer, a computing device, etc.) using simulationprograms such as OSLO, ZEMAX, CODE V, or a proprietary simulator. Thefigures of merit can be appropriately weighted to include and/oremphasize the peripheral region at a distance equal to the distancebetween the PRL and the fovea. In some implementations, the figures ofmerit can exclude image quality at the fovea to further improveperipheral quality. In some implementations, the figures of merit caninclude image quality at the fovea as well as at a particular locationof the peripheral retina and/or a region around the fovea. As discussedbelow, the first and the second surfaces 505 and 510 of the optic 500can be selected using an eye model that is based on population averagevalues for various parameters of the eye. Alternately, the first and thesecond surfaces 505 and 510 of the optic 500 can be selected using aneye model that is specific to a patient. Some of the patient's eyecharacteristics that can be taken into consideration to determine firstand the second surfaces 505 and 510 of the optic 500 can include: (i)Corneal radius of curvature and asphericity; (ii) Axial length; (iii)Retinal curvature; (iv) Anterior chamber depth; and/or (v) Expected lensposition.

An advantage of an optic including first and second surfaces havingsurface characteristic described above is that once the characteristicsof the first and second surfaces have been determined, the optic can befabricated as a single optical component with uniform refractive index.Additionally, the symmetrical nature of the optic can confer a number ofadvantages in the diagnostics and surgery procedure as discussed below.For example, as discussed above, a patient who does not have awell-established PRL can benefit from a lens including an optic similarto optic 500 described above since the patient can choose theorientation and the eccentricity that provides the best visual outcome.The optic 500 can improve the peripheral optical quality generally for apatient without a well-established PRL at a position that provides thebest visual outcome for the patient so that the patient can develop thePRL at that position. Some of the lenses that are configured for use bypatients with AMD can degrade quality of vision at the fovea. However,as discussed below, the optic 500 can be configured to provide goodimage quality at the fovea as well as a location of the peripheralretina. So it may be attractive to consider an optic similar to theoptic 500 above for a patient with beginning AMD, where some otherimplementations of lenses that configured to improve image quality at aperipheral retina location may degrade foveal image quality tounacceptable levels. Since the onset of AMD is generally later thancataract, there may be a large group of patients undergoing cataractsurgery who have early signs of AMD, and thus later would benefit from alens including an optic similar to optic 500 and for whom the on-axisperformance (foveal image quality) of the alternative lens configurationwould be unacceptable. Additionally, the surgeon does not need to orientan IOL including an optic similar to the optic 500 when implanting it.Furthermore, the optic 500 can be configured to have a thickness thatcan provide manufacturing benefits as compared to other lens designs.Additionally, the surfaces of the optic 500 can be configured to bedevoid of tilt which can also provide manufacturing benefits.

As discussed above, the surface sag of the first surface 505 and/or thesecond surface 510 can be varied by selecting different values of thecurvature, conic constant, and other parameters in equation (1). FIG. 5Billustrates the surface sag of the first surface 505 for animplementation of the optic 500 and FIG. 5C illustrates the surface sagof the second surface 510 for the implementations of the optic 500. Itis noted that from FIGS. 5B and 5C that the first and second surface 505and 510 are aspheric.

Depending on the patient's refractive needs, the first surface 505and/or the second surface 510 of the optic 500 can be convex or concave.For example, in the illustrated implementation, both the first surface505 and the second surface 510 are convex. However, in otherimplementations, the first surface 505 can be concave and/or the secondsurface 510 can be concave. The shape and curvature of the first surface505 and/or second surface 510 can be selected based on the patient'svisual requirements as well the patient's ocular characteristics.

In various implementations, the optic 500 can be configured such thatthe refractive properties of the optic 500 can be changed in response tothe eye's natural process of accommodation. For example, the optic 500can comprise a deformable material that can compress or expand inresponse to ocular forces applied by the capsular bag and/or the ciliarymuscles. For example, the optic 500 can be configured to change theirshape in response to ocular forces in the range between about 1 gram toabout 10 grams, 5 to 10 grams, 1 to 5 grams, about 1 to 3 grams orvalues therebetween to provide an optical power change between about 0.5Diopters and about 6.0 Diopters. In various implementations, the optic500 can comprise materials such as acrylic, silicone,polymethylmethacrylate (PMMA), block copolymers ofstyrene-ethylene-butylene-styrene (C-FLEX) or other styrene-basecopolymers, polyvinyl alcohol (PVA), polystyrenes, polyurethanes,hydrogels, etc. The optic 500 can comprise structures and materials thatare described in U.S. Publication No. 2013/0013060 which is incorporatedby reference herein in its entirety.

As discussed above, the optic 500 can be incorporated in an IOL that isprovided with a haptic that holds the IOL in place when implanted in theeye. The haptic can comprise a biocompatible material that is suitableto engage the capsular bag of the eye, the iris 230, the sulcus and/orthe ciliary muscles of the eye. For example, the haptic can comprisematerials such as acrylic, silicone, polymethylmethacrylate (PMMA),block copolymers of styrene-ethylene-butylene-styrene (C-FLEX) or otherstyrene-base copolymers, polyvinyl alcohol (PVA), polystyrene,polyurethanes, hydrogels, etc. In various implementations, the hapticcan include a one or more arms that are coupled to the optic 500. Forexample, the haptic can be configured to have a structure similar to thestructure of the biasing elements disclosed in U.S. Publication No.2013/0013060 which is incorporated by reference herein in its entirety.In various implementations, the haptic can include one or more arms thatprotrude into the optic 500. In various implementations, the haptic canbe configured to move the optic 500 along the optical axis of the eye inresponse to ocular forces applied by the capsular bag and/or the ciliarymuscles. For example, the haptic can include one or more hinges tofacilitate axial movement of the optic. As another example, the hapticcan include springs or be configured to be spring-like to effectmovement of the optic 500. In this manner, the axial position of theoptic 500 can be varied in response to ocular forces to provide visionover a wide range of distances. An IOL that is configured to change theaxial position of the optic and/or shape and size of the optic inresponse to ocular forces applied by the capsular bag and/or ciliarymuscles can be referred to as an accommodating lens.

The optic 500 is configured such that light incident on the cornea atoblique angles to the optical axis 280 of the eye is focused on alocation of the peripheral retina away from the fovea. The light can beincident in the vertical field of view or the horizontal field of view.For example, the optic 500 can be configured to focus light incident atoblique angles between about 5 degrees and about 30 degrees with respectto the optical axis 280 of the eye, between about 10 degrees and about25 degrees with respect to the optical axis 280 of the eye, betweenabout 15 degrees and about 20 degrees with respect to the optical axis280 of the eye, or there between at a location on the peripheral retinaaway from the fovea. As discussed above, the optic 500 can also beconfigured such that light incident on cornea along a direction parallelto the optical axis is focused on the fovea for those patients withearly AMD who still have some foveal vision. For example, some patientsmay have parts of the fovea covered by a scotoma instead of a centralscotoma. Such patients may have some residual foveal vision and canbenefit from incident light being focused at the fovea by the optic 500.Additionally, the optic 500 can also be configured to accommodate tofocus objects located at different distances on to the retina (e.g., ata location on the periphery of the retina and/or the fovea) in responseto ocular forces exerted by the capsular bag and/or ciliary muscles.

The implementations of the optic 500 described in this disclosure can beconfigured to correct lower order errors (e.g. sphere and cylinder),higher order aberrations (e.g., coma, trefoil) or both resulting fromthe oblique incidence of light in the image formed at a location of theperipheral retina. The characteristic of the first surface 505 and/orthe second surface 510 of the optic 500, the thickness of the optic 500,etc. can be designed such that the optic 500 can focus light incident ata plurality of oblique angles (e.g., between about −25 degree and about+25 degrees with respect to the optical axis of the eye) in an areaaround a location on the peripheral retina spaced away from the foveawith sufficient visual contrast. This is explained in further detailbelow with respect to FIG. 5D.

FIG. 5D shows a cross-section view of an eye with a central scotoma atthe fovea 260 and implanted with an implementation of an IOL includingthe optic 500 illustrated in FIG. 5A. Light from an object is incidentin a range of oblique angles between θ₁ and θ₂ with respect to theoptical axis 280 and are focused by the optic 500 in an area 525disposed around a location 520 on the peripheral retina disposed awayfrom the fovea 260. For most patients θ₁ can be between 3 degrees and 5degrees and θ₂ can be between 10 degrees and 35 degrees. The location520 can be located at a distance r from the fovea 260 along a directionthat makes an angle θ₃ with respect to a tangential line 530intersecting the retina at the fovea 260 and lying in the tangentialplane. Although, not shown in FIG. 5D, the location 520 can be locatedat a distance r from the fovea 260 along a direction that makes an angleθ₄ with respect to a tangential line (not shown) intersecting the retinaat the fovea 260 and lying in the sagittal plane. The angles θ₃ and θ₄can have a value greater than or equal to 0 degrees and less than 30degrees. The distance r can have a value between about 0.5 mm and about4 mm.

The area 525 can be described as the region between a first region whichis the base of a cone having a semi angle of θ₁ degrees with respect tothe optical axis 280 and a second region which is the base of a conehaving a semi angle of about θ₂ degrees with respect to the optical axis280. Accordingly, the angular width of the area 525 is given by (θ₂−θ₁).For most patients, the angular width of the area 525 can be betweenabout 5 degrees and about 30 degrees. Without any loss of generality,the area 525 can include locations that are within about 2-5 mm from thefovea 260. The area 525 can have an angular extent Δθ_(1h) in thehorizontal plane and an angular extent Δθ_(1v) in the vertical plane, asshown in FIG. 5D-3. In various implementations, the angular extentΔθ_(1v) can be zero or substantially small such that the area 525 is ahorizontal line above or below the fovea 260. Alternately, the angularextent Δθ_(1h) can be zero or substantially small such that the area 525is a vertical line to the left or the right of the fovea 260. In someembodiments, the angular extent Δθ_(1v) and the angular extent Δθ_(1h)can be equal such that the area 525 is circular. In some otherimplementations, the angular extent Δθ_(1h) and the angular extentΔθ_(1v) can be unequal such that the area 525 is elliptical. In variousimplementations, the angular extent Δθ_(1v) and the angular extentΔθ_(1h) have values such that the area 525 includes the fovea 260.However, in other implementations, the angular extent Δθ_(1v) and theangular extent Δθ_(1h) can have values such that the area 525 does notinclude the fovea 260.

In various implementations, the optic 500 can be configured to focusincident light at the PRL 520. However, in various implementations, theIOL 500 can be configured to focus the incident light in front of orbehind the PRL 520 such that the incident light is defocused at the PRL520 as shown in 3J.

As discussed above, the optic 500 is symmetric such that the imagequality in an annular region around the fovea is uniform. Such an opticcan be used by patients who do not have a well-developed PRL. Suchpatients can orient their eyes and/or heads to select the position thataffords the best visual quality. The annular region can be between afirst region and a second region. The first region can be the base of acone having a semi angle of θ₁ degrees with respect to the optical axis280 and the second region can be the base of a cone having a semi angleof about θ₂ degrees with respect to the optical axis 280. Accordingly,the angular width of the annular region is given by (θ₂−θ₁). For mostpatients θ₁ can be between 3 degrees and 5 degrees and θ₂ can be between10 degrees and 35 degrees. Accordingly, for most patients, the angularwidth of the annular region can be between about 5 degrees and about 30degrees. Without any loss of generality, the annular region can includelocations that are within about 2-5 mm from the fovea.

Generally, patients with AMD experience greater improvement in theirvision when refractive errors arising from the oblique astigmatism andcoma are corrected for image formed at a location in the peripheralretina than patients without AMD at similar retinal eccentricities.Accordingly, the characteristics of the first surface 505, the secondsurface 510, the thickness of the optic 500 and its orientation whenimplanted in the eye can be adjusted such that the refractive errors dueto relative peripheral defocus, oblique astigmatism and coma in an imageproduced at a location of the peripheral retina by the optic 500 arereduced. The optic 500 can also be configured to provide good visualquality at the fovea 260 for those patients who have early stage AMD.

In contrast to optics and IOLs that are configured to improve imagequality at the fovea, the optic 500 is configured to improve imagequality in a region of the peripheral retina that is offset from thefovea. For example, the optic 500 can be configured to improve imagequality in an annular zone surrounding the fovea 260 as shown in FIG.5D-1. The annular zone can include an area 545 between an innerperiphery 535 surrounding the fovea and an outer periphery 540surrounding the fovea 260. The inner periphery 535 can include retinallocations at an eccentricity between about 1 degree and about 10degrees. Without any loss of generality, as used herein, the termeccentricity refers to the angle between a normal to the retina at thelocation of interest and the optical axis of the eye which intersectsthe retina at the fovea. Accordingly, the fovea is considered to have aneccentricity of about 0 degrees. The outer periphery 540 can includeretinal locations at an eccentricity between about 3 degrees and about25 degrees. Although in FIG. 5D-1 the optic 500 is not configured toimprove image quality in the foveal region, in various implementations,the area 545 in which the optic 500 is configured to improve imagequality can extend to the foveal region and include the fovea 260 forpatient who have residual foveal vision. In such implementations, theoptic 500 can be configured to provide good image quality at the foveaas well as at peripheral retinal locations at an eccentricity betweenabout 1 degree and about 25 degrees. In various implementations, theregion 545 can be symmetric about the fovea 260. In someimplementations, a projection of the region 545 on a plane tangential tothe retina at the fovea 260 can be circular, oval or any other shape.

As another example, the optic 500 can be configured to improve imagequality in a region 548 surrounding a preferred retinal location (e.g.,location 520 as shown in FIG. 5D) offset from the fovea as shown in FIG.5D-2. The preferred retinal location can be located at an eccentricitybetween about 1 degree and about 25 degrees. The region 548 surroundingthe preferred retinal location 520 can include retinal locations at aneccentricity between about 1 degree and about 25 degrees.

As discussed above, the image quality at the region of the peripheralretina can be improved by optimizing the image quality produced by theoptic 500 such that optical errors (e.g., peripheral astigmatism, coma,trefoil, etc.) are reduced at the peripheral retinal region. Forexample, the image quality at the peripheral retinal region can beincreased by correcting optical errors at the peripheral retinal region,correcting for corneal astigmatism at the peripheral retinal region,reducing optical errors resulting from oblique astigmatism at theperipheral retinal region, reducing coma at the peripheral retinalregion and/or reducing other higher order aberrations at the peripheralretinal region.

The improvement in the image quality at the peripheral retinal regionprovided by the optic 500 can be measured using different figures ofmerit discussed above. For example, an optic (e.g., the optic 500) thatis configured to improve image quality in the peripheral retinal regioncan provide a MTF greater than a threshold value (MTF_(THR)) at one ormore spatial frequencies for an image produced at the desired peripheralretinal region. Similarly, an optic that is configured to improve imagequality in the foveal region can provide a MTF greater than a thresholdvalue (MTF_(THR)) at one or more spatial frequencies for an imageproduced at the foveal region. The threshold value (MTF_(THR)) can besubjective and be determined based on the patient's needs and ophthalmiccondition. For example, some patients may be satisfied with an imagequality having a MTF greater than 0.1 for spatial frequencies between 10cycles/mm and 50 cycles/mm. Some other patients may desire a MTF greaterthan 0.5 for spatial frequencies between 1 cycle/mm and 100 cycles/mm.Accordingly, the threshold MTF value (MTF_(THR)) can vary depending onthe lens design and the patient's needs. The increase in MTF value canbe correlated with an improvement in the patient's ability to readvarious lines in an eye chart. For example, without any loss ofgenerality, an increase in MTF from 0.7 to 0.8 can correspond to about15% contrast sensitivity improvement, or 1 line of visual acuity (VA).Similarly, an increase in MTF from 0.7 to 0.9 can correspond to about30% increase in contrast sensitivity or 2 lines VA.

FIG. 5E which shows the variation in image quality versus eccentricityfor an implementation of an optic configured to improve image quality ata peripheral retinal region and an optic configured to improve imagequality at the fovea region. Curve 550 shows the variation of MTF versuseccentricity for an optic configured to improve image quality at aperipheral retinal region while curve 555 shows the variation of MTFversus eccentricity for an optic configured to improve image quality atthe foveal region. As shown in FIG. 5E the optic configured to improveimage quality at a peripheral retinal region provides a MTF greater thana threshold value (MTF_(THR)) at one or more spatial frequencies at aneccentricity between 1 degree and 25 degrees and −1 degree and −25degrees such that an image produced in the peripheral retinal region atan eccentricity between 1 degree and 25 degrees and −1 degree and −25degrees has sufficient contrast sensitivity. In various implementations,the optic may be configured to improve image quality at a peripheralretinal region at the expense of foveal vision. For example, the opticconfigured to improve image quality at a peripheral retinal region mayprovide a MTF less than the threshold value (MTF_(THR)) in the fovealregion (e.g., at an eccentricity between −1 degree and 1 degree). Incontrast, an optic configured to improve foveal vision will provide anMTF greater than the threshold value (MTF_(THR)) for an image producedin the foveal region. In some implementations, the optic configured toimprove image quality at a peripheral retinal region may also beconfigured to provide a MTF value greater than the threshold value(MTF_(THR)) at the foveal region as shown by curve 560.

One way to configure the optic 500 to reduce optical errors at aperipheral retinal region is to determine the surface profiles of theoptic 500 that reduce optical errors due to oblique astigmatism and comaat the peripheral retinal region when light incident on the eyeobliquely with respect to the optical axis 280 is focused by the IOLsystem 500 at the peripheral retinal region. Using a lens designingsystem various surface characteristics of the first and/or secondsurface 505 and 510 of the optic 500 can be determined that reduceoptical errors at a peripheral location of the retina. The varioussurface characteristics can include curvatures, surface sags, radius ofcurvatures, conic constant, axial thickness, area of the optical zone,diffractive features, echelletes and/or prismatic features provided withthe optic, etc. In various implementations, a portion of the firstsurface or the second surface can include redirecting elements describedherein and that are similar to the prismatic features and/or diffractivefeatures described in U.S. Provisional Application No. 61/950,757, filedon Mar. 10, 2014, titled “INTRAOCULAR LENS THAT IMPROVES OVERALL VISIONWHERE THERE IS A LOSS OF CENTRAL VISION,” which is incorporated byreference herein in its entirety. The redirecting elements can beconfigured to redirect light incident on the eye along the optical axisand/or at an angle to the optical axis to one or more locations on theretina.

The surface characteristics can be determined using an eye model that isbased on average population statistics. Alternately, the surfacecharacteristics can be determined by using an eye model that is specificto each patient and constructed using a patient's individual ocularcharacteristics. Some of the ocular characteristics that can be takeninto consideration when determining the characteristics of the surfacesof the optic 500 can include corneal radius of curvature andasphericity, axial length, retinal curvatures, anterior chamber depth,expected lens position, location of image on the peripheral retina, sizeof the scotoma, optical and physical characteristics of the existinglens, peripheral aberrations, etc. As discussed above, depending on thepatient's needs, the first and/or the second surface 505, 510 of theoptic 500 can be symmetric and/or include higher (e.g., second, fourth,sixth, eighth) order aspheric terms. The first and/or second surface505, 510 of the optic 500 can be parabolic, elliptical, a Zernikesurface, an aspheric Zernike surface, a toric surface, a biconic Zernikesurface, etc.

The optic 500 can be configured to provide an optical power betweenabout 0.5 Diopter and +34.0 Diopter. For example, the optic 500 can beconfigured to provide an optical power between about 0.5 Diopter andabout 5.0 Diopter, between about 1.0 Diopter and 6.0 Diopter, betweenabout 2.0 Diopter and about 7.0 Diopter, between about 3.0 Diopter and8.0 Diopter, between about 4.0 Diopter and 9.0 Diopter, between about5.0 Diopter and 10.0 Diopter, between about 10.0 Diopter and about 15.0Diopter, between about 15.0 Diopter and about 20.0 Diopter, betweenabout 20.0 Diopter and 25.0 Diopter, between about 25.0 Diopter andabout 30.0 Diopter and between about 30.0 Diopter and 34.0 Diopter. Theoptic 500 can be configured to provide cylindrical power between about0.5 to about 5.0 Diopters to provide astigmatic correction. In variousimplementations, the optic 500 can be multifocal having multiple opticalzones configured to provide a range of add powers between 0.5 Diopterand about 6.0 Diopter. In various implementations, the optic 500 caninclude filters and/or coatings to absorb short wavelengths that candamage the retina further. For example, in some implementations, theoptic 500 can include a blue blocking filter.

FIG. 6A illustrates the MTF at a PRL located at an eccentricity of 10degrees for different spatial frequencies between 0 cycles/mm and 30cycles/mm for a standard toric IOL (e.g., TECNIS®). As discussed above,the MTF is calculated (or simulated) for both sagittal rays andtangential rays. The MTF can be calculated (or simulated) using anoptical simulation program such as, for example, OSLO, ZEMAX, CODE V,etc. As observed from FIG. 6A, the MTF at the PRL is less than 0.4 for aspatial frequency of 30 cycles/mm for sagittal focus, while the modulusof the OTF is less than 0.9 for a spatial frequency of 30 cycles/mm fortangential focus. The patient can benefit from increase in the MTF forat least the sagittal focus. FIG. 6B illustrates the MTF at the PRL fordifferent spatial frequencies between 0 cycles/mm and 30 cycles/mm whenthe patient is implanted with a standard toric IOL that is configured toprovide optimal astigmatic correction for the periphery. From FIG. 6B,it is noted that the MTF for both tangential and sagittal foci isimproved as compared to a standard toric IOL and is between 0.6 and 0.7for tangential foci for spatial frequency of 30 cycles/mm and between0.8 and 0.9 for sagittal foci for spatial frequency of 30 cycles/mm. Anoptic 500 whose first and second surface can be described by equation(1) provided above can provide a MTF greater than 0.8 for bothtangential and sagittal foci for spatial frequency of 30 cycles/mm asobserved from FIG. 6C. Accordingly, the optic 500 described above canimprove the image quality (e.g., contrast ratio of the image) atperipheral retinal location. In various implementations, the optic 500can be configured to provide a MTF at a spatial frequency of 30cycles/mm greater than 0.5, greater than 0.6, greater than 0.7, greaterthan 0.8, or greater than 0.9. For example, the optic 500 can beconfigured to provide a MTF at a spatial frequency of 30 cycles/mmgreater than 0.5, greater than 0.6, greater than 0.7, greater than 0.8and greater than 0.9 for eccentricities between about 7 degrees and 13degrees from the fovea.

As discussed above, the an implementation of an optic similar to theimplementation of optic 500 discussed above having surfaces described byequation (1) above can provide better image quality at the fovea 260 aswell as at a peripheral retinal location as compared to anotherimplementation of an optic that is configured to provide good imagequality at a peripheral retinal location. FIG. 6D illustrates the MTF atthe fovea for different spatial frequencies between 0 cycles/mm and 100cycles/mm for both tangential and sagittal foci provided by animplementation of a standard toric IOL (e.g., TECNIS®) with opticalpower optimized for a PRL. FIG. 6E illustrates the MTF at the fovea fordifferent spatial frequencies between 0 cycles/mm and 100 cycles/mm forboth tangential and sagittal foci provided by an implementation of anoptic similar to the optic 500. It is noted from FIG. 6D theimplementation of a standard toric IOL (e.g., TECNIS®) with opticalpower optimized for a PRL has MTF less than 0.5 for spatial frequenciesgreater than 30 cycles/mm which indicates degraded contrast sensitivityfor image formed at the fovea. In contrast, an optic similar to theoptic 500 has a MTF greater than 0.9 for spatial frequencies upto 100cycles/mm which indicates that an image formed at the fovea has goodcontrast sensitivity in addition to an image formed at a peripheralretinal location having good contrast sensitivity.

It is conceived that the implementations of optic 500 having twoaspheric surfaces that are configured to improve image quality at aperipheral retinal location by correcting optical errors arising fromoblique incidence of light (e.g., oblique astigmatism and coma) canimprove the MTF by at least 5% (e.g., at least 10% improvement, at least15% improvement, at least 20% improvement, at least 30% improvement,etc.) at a spatial frequency of 30 cycles/mm for both tangential andsagittal foci at a peripheral retinal location at an eccentricitybetween about 1 degree and about 25 degrees with respect to the fovea ascompared to the MTF at a spatial frequency of 30 cycles/mm provided byan IOL that is configured to improve image quality at the fovea at thesame peripheral retinal location.

It is conceived that the implementations of optic 500 having twoaspheric surfaces that are configured to improve image quality at aperipheral retinal location by correcting optical errors arising fromoblique incidence of light (e.g., oblique astigmatism and coma) canprovide a MTF greater than 0.2 at a spatial frequency of 30 cycles/mmfor both tangential and sagittal foci, greater than 0.3 at a spatialfrequency of 30 cycles/mm for both tangential and sagittal foci, greaterthan 0.4 at a spatial frequency of 30 cycles/mm for both tangential andsagittal foci, greater than 0.5 at a spatial frequency of 30 cycles/mmfor both tangential and sagittal foci, greater than 0.6 at a spatialfrequency of 30 cycles/mm for both tangential and sagittal foci, greaterthan 0.7 at a spatial frequency of 30 cycles/mm for both tangential andsagittal foci, greater than 0.8 at a spatial frequency of 30 cycles/mmfor both tangential and sagittal foci or greater than 0.9 at a spatialfrequency of 30 cycles/mm for both tangential and sagittal foci at aperipheral retinal location between about 1 degree and about 25 degreeswith respect to the fovea.

The optic 500 can be configured to provide one of distance vision, nearvision, or intermediate distance vision, distance vision and nearvision, distance vision and intermediate distance vision, near visionand intermediate distance vision or all. Various implementations of theoptic 500 include spherical aberrations to correct for corneal sphericalaberrations. As discussed above, diffractive optical elements can beprovided on one of the surfaces (e.g., the spherical surface) of theoptic 500 to provide near reading zone or to provide depth of focus. Theoptic 500 can be configured as an add-on lens that is provided inaddition to an existing lens (e.g., a natural lens or another IOL) inthe eye. The one or more surfaces of the optic 500 can be designed fordifferent types of patch configurations.

In various implementations, if a patient's cornea is astigmatic (e.g.,toric), then the optic 500 described above can be configured as a toric,such that the image quality around the optical axis 515 is uniform.Although, only aspheric coefficients of first to fourth order areincluded in equation (1) above, the first and second surfaces of theoptic 500 can be described aspheric coefficients of higher orders. Forexample, the first and second surfaces of the optic 500 can be describedby an equation including aspheric coefficients of orders upto 14. Inother implementations, the first and second surfaces of the optic 500can be described by aspheric coefficients having order less than 4(e.g., 1, 2 or 3).

The optic 500 can have a clear aperture. As used herein, the term “clearaperture” means the opening of a lens or optic that restricts the extentof a bundle of light rays from a distant source that can imaged orfocused by the lens or optic. The clear aperture can be circular andspecified by its diameter. Thus, the clear aperture represents the fullextent of the lens or optic usable for forming the conjugate image of anobject or for focusing light from a distant point source to a singlefocus or to a plurality of predetermined foci, in the case of amultifocal optic or lens. It will be appreciated that the term clearaperture does not limit the transmittance of the lens or optic to be ator near 100%, but also includes lenses or optics having a lowertransmittance at particular wavelengths or bands of wavelengths at ornear the visible range of the electromagnetic radiation spectrum. Insome embodiments, the clear aperture has the same or substantially thesame diameter as the optic 500. Alternatively, the diameter of the clearaperture may be smaller than the diameter of the optic 500. In variousimplementations of the optic 500 described herein the clear aperture ofthe optic 500 can have a dimension between about 3.0 mm and about 7.0mm. For example, the clear aperture of the optic 500 can be circularhaving a diameter of about 5.0 mm.

The optic 500 can include prismatic, diffractive elements, echelletes oroptical elements with a gradient refractive index (GRIN) profile toprovide a larger depth of field or near vision capability. The optic 500can include one or more apertures in addition to the clear aperture tofurther enhance peripheral image quality.

The implementations of optic 500 described herein can use additionaltechniques to extend the depth of focus. For example, the optic 500 caninclude diffractive features (e.g., optical elements with a GRINprofile, echelletes, etc.) to increase depth of focus. As anotherexample, in some embodiments, a refractive power and/or base curvatureprofile(s) of an intraocular lens surface(s) may contain additionalaspheric terms or an additional conic constant, which may generate adeliberate amount of spherical aberration, rather than correct forspherical aberration. In this manner, light from an object that passesthrough the cornea and the lens may have a non-zero sphericalaberration. Because spherical aberration and defocus are relatedaberrations, having fourth-order and second-order dependence on radialpupil coordinate, respectively, introduction of one may be used toaffect the other. Such aspheric surface may be used to allow theseparation between diffraction orders to be modified as compared to whenonly spherical refractive surfaces and/or spherical diffractive basecurvatures are used. An additional number of techniques that increasethe depth of focus are described in detail in U.S. patent application.Ser. No. 12/971,506, titled “SINGLE MICROSTRUCTURE LENS, SYSTEMS ANDMETHODS,” filed on Dec. 17, 2010, and incorporated by reference in itsentirety herein. In some embodiments, a refractive lens may include oneor more surfaces having a pattern of surface deviations that aresuperimposed on a base curvature (either spherical or aspheric).Examples of such lenses, which may be adapted to provide lensesaccording to embodiments of the present invention, are disclosed in U.S.Pat. No. 6,126,286, U.S. Pat. No. 6,923,539 and U.S. Patent ApplicationNo. 2006/0116763, all of which are herein incorporated by reference intheir entirety.

Lens Designs to Improve Peripheral Vision

The lenses described below include implementations of standard lenses,multi-refractive lenses, lenses with asymmetric Zernike surfaces, dualoptic lenses, piggyback lenses, etc. that can be configured to focusobliquely incident light at a location on the peripheral retina awayfrom the fovea.

Embodiments of the lenses discussed herein are configured to redirectlight incident at angles in a range of angle between about ±30 degreeswith respect to the optical axis 280 of the eye at a location on theperipheral retina away from the fovea. For example, the implementationsof the lenses discussed herein can be configured to focus light incidentat an angle between ±10 degrees with respect to the optical axis 280 ina vertical plane with a contrast sensitivity of at least 0.5 for aspatial frequency of 30 cycles/mm. As another example, theimplementations of the lenses discussed herein can be configured tofocus light incident at an angle between ±25 degrees with respect to theoptical axis 280 in a horizontal plane with a contrast sensitivity of atleast 0.5 for a spatial frequency of 30 cycles/mm. As discussed above,the MTF refers to how much of the contrast ratio in the object ispreserved when the object is imaged by the lens. A modulus of the OTF of1.0 indicates that the IOL does not degrade the contrast ratio of theobject and modulus of the OTF of 0 indicates that the contrast ratio isdegraded such that adjacent lines in the object cannot be resolved whenthe object is imaged by the lens. Accordingly, the MTF is a measure ofcontrast sensitivity or sharpness.

The MTF for the various embodiments of IOLs described below iscalculated for both sagittal rays (e.g., 517 s) and tangential rays(e.g., 517 t) originating from an object 516 disposed with respect tothe point of intersection of the lens (e.g. lens 500) and the opticalaxis 280. The MTF is calculated for various off-axis positions of theobject 516 represented by coordinates along the x-direction and they-direction in a Cartesian coordinate system in which the point ofintersection of the lens (e.g. lens 500) and the optical axis 280 isdisposed at the origin of the Cartesian coordinate system and theoptical axis (e.g. optical axis 280) is along the z-direction, as shownin FIG. 5F. In various implementations, the point of intersection of thelens (e.g. lens 500) and the optical axis 280 can coincide with thegeometric of the IOL and/or the geometric center of a surface of theIOL.

Embodiment 1

A patient implanted with a standard IOL having a tonic surface (such asTECNIS® toric IOL) that is configured to correct for corneal astigmatismmay be able to view objects with some contrast sensitivity in theabsence of central vision. FIG. 7A shows a cross-section view of anembodiment of a standard intraocular lens (IOL) configured to provideimproved vision at a location of the peripheral retina. However, sincethe standard toric IOL is optimized for foveal vision (or centralvision), the contrast sensitivity for light incident at oblique angles(e.g. between about ±10 degrees with respect to the optical axis 2501 inthe tangential plane and/or between about ±30 degrees with respect tothe optical axis 2501 in the sagittal plane) may not be high. Forexample, a standard IOL can provide an average MTF of about 0.7 for aneccentricity between 7-13 degrees for spatial frequency of 30 cycles/mm.Generally, an improvement in the MTF from 0.7 to 0.8 can provide asubstantial visual benefit for a patient with AMD. For example, withoutany loss of generality, an increase in MTF from 0.7 to 0.8 correspondsto about 15% contrast sensitivity improvement, or 1 line of visualacuity (VA). Various implementations described herein can provide 2lines VA and 30% contrast sensitivity more. The improvement in the VAand contrast sensitivity can be more if the peripheral power errors arelarger. Accordingly, a patient with AMD can benefit from an increase inMTF at a peripheral retinal location. In various implementations, thespherical power of the implementation of the standard toric IOLdescribed above in Embodiment 1 can be optimized to provide increasedcontrast sensitivity at a PRL away from the fovea. For example, thespherical power can be optimized by selecting the design that willprovide the highest MTF values at the spatial frequency range ofrelevance for the patient through evaluation in an eye model using thepatient's biometric data.

Embodiment 2

FIG. 7B shows a cross-section view of an embodiment of an enhanced toricIOL configured to provide improved vision at a location of theperipheral retina. Such lenses are also described in U.S. applicationSer. No. ______ filed concurrently herewith on Mar. 10, 2015, titled“ENHANCED TORIC LENS THAT IMPROVES OVERALL VISION WHERE THERE IS A LOCALLOSS OF RETINAL FUNCTION,” Attorney Docket No. AMOLNS.055A2, which isincorporated herein by reference in its entirety. The enhanced toriclens can include a toric surface and a spherical surface opposite thetoric surface. The sagittal depth or the distance from the center of thetoric surface to an imaginary flat plane joining the ends of theanterior toric surface, z, can be given by equation (3) below:

As another example, the enhanced toric surface can be describedmathematically by equation (2) below:

$\begin{matrix}{z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {\sum\limits_{i = 1}^{4}{\alpha_{i}r^{2\; i}}} + {\sum\limits_{i = 1}^{N}{A_{i}{Z_{i}\left( {\rho,\varphi} \right)}}}}} & (2)\end{matrix}$

where z is the sag of the surface, c is the curvature of the surface, rthe radial distance from the optical axis 515, k the conic constant, athe aspheric coefficients, A are the Zernike coefficients and Z are theZernike polynomials. The fifth and the sixth Zernike coefficientscorrespond to the astigmatic terms and the seventh and the eighthZernike coefficients correspond to the coma term. The asphericcoefficients α are rotationally symmetric. In various implementations,the surface sag (z) of the toric surface can include upto eighth orderaspheric terms. In some implementations, the surface sag (z) of thetoric surface can include less than eighth order (e.g., 0, 2, 4, 6) orgreater than eighth order (e.g., 10 or 12) aspheric terms. Alternately,the toric surface can be described by up to 34 Zernike coefficients. Insome implementations, the toric surface can be described by less than 34Zernike coefficients. In some implementations, the toric surface can bedescribed by more than 34 Zernike coefficients. Additionally, thefirst/and or second surface can be described as a combination of theaspheric and Zernike coefficients. The toric surface that reducesperipheral errors can be determined by optimizing the Zernikecoefficients for the astigmatic and the coma terms. The toric IOL caninclude redirecting elements similar to the prismatic features and/ordiffractive features described herein. The redirecting elements can beconfigured to redirect light incident on the eye along the optical axisand/or at an angle to the optical axis to one or more locations on theretina.

Optical simulations indicate that the average MTF for the implementationof a lens with an enhanced toric surface as described above at aperipheral retinal location at an eccentricity between about 7-degreesand about 13-degrees can be greater than 0.8 at a spatial frequency of30 cycles/mm for light incident in the tangential as well as thesagittal planes. Although, the implementation of the IOL with anenhanced toric surface has good contrast sensitivity for a large fieldof view along the horizontal angle, the contrast sensitivity couldreduce if IOL is tilted during or after implantation or the angle offixation changes. Additionally, the foveal image quality provided by alens with an enhanced toric surface may be degraded.

Embodiment 3

FIG. 7C shows a cross-section view of an embodiment of a symmetricsingle optic IOL configured to provide improved vision at a location ofthe peripheral retina. The symmetric single optic lens can be symmetricabout the optical axis such that the image quality in a region aroundthe optical axis is uniform. The symmetric single optic lens illustratedin FIG. 7C can have surfaces that are described by equation (1) above.In various implementations, the surfaces of the symmetric single opticlens can be spherical, aspheric, a biconic Zernike surface, conic, etc.The symmetric single optic lens can be configured to provide an averageMTF greater than about 0.7 at spatial frequency of 30 cycles/mm foreccentricity at a peripheral retinal location at an eccentricity betweenabout 7-degrees and about 13-degrees for light incident obliquely withrespect to the optical axis and focused at a peripheral retinal locationas well as a contrast sensitivity greater than about 0.7 for spatialfrequency of 30 cycles/mm for light incident parallel to the opticalaxis and focused at the fovea 260.

Embodiment 4

FIG. 7D shows a cross-section view of an embodiment of an asymmetricsingle optic IOL configured to provide improved vision at a location ofthe peripheral retina. The embodiment illustrated in FIG. 7D can includeone surface that is spherical and another surface that is aspheric. Forexample, in various implementations, one surface of the lens can be abiconic Zernike surface. The lens can have a central thickness t_(cen)along the optical axis. The surfaces of the lens can be configured suchthat the thickness t₁ of an edge of the lens can be greater than thethickness t₂ of the other edge of the lens. Accordingly, the IOL canappear wedge shaped. In various implementations, the central thicknesst_(cen) can be less than, greater than or equal to either of the edgethicknesses t₁ or t₂.

The sagittal depth or the distance from the center of the asphericsurface to an imaginary flat plane joining the ends of the asphericsurface, z, can be given by the following equation:

${z = {\frac{{c_{x}x^{z}} + {c_{y}y^{z}}}{1 + \sqrt{1 - {\left( {1 + k_{x}} \right)c_{x}^{z}x^{z}} - {\left( {1 + k_{y}} \right)c_{y}^{z}y^{z}}}} + {\sum\limits_{i = 1}^{16}{\alpha_{i}x^{i}}} + {\sum\limits_{i = 1}^{16}{\beta_{i}y^{i}}} + {\sum\limits_{i = 1}^{16}{A_{i}{Z_{i}\left( {\rho,\phi} \right)}}}}},$

where x and y are distances in the Cartesian coordinate system from thecenter of the curvature of the surface, c_(x) and c_(y) are thecurvatures along the x and the y axes, k_(x) and k_(y) are the conicconstants along the x and the y axes, A_(i) are the Zernike coefficientsand Z_(i) are the standard Zernike polynomials. The implementation ofthe lens illustrated in FIG. 7D can advantageously provide the samecontrast sensitivity at the peripheral retinal location regardless ofthe tilt of the lens and/or the angle of fixation. In variousimplementations, the lens illustrated in FIG. 7D could provide anaverage MTF greater than about 0.8 at a spatial frequency of 30cycles/mm at a peripheral retinal location at an eccentricity betweenabout 7-degrees and about 13-degrees.

Embodiment 5

FIG. 7E shows a cross-section view of an embodiment of a thick symmetricIOL configured to provide improved vision at a location of theperipheral retina. The lens illustrated in FIG. 7E can be similar to theoptic 500 illustrated in FIG. 5A. In various implementations of the lensillustrated in FIG. 7E, the surfaces of the can be aspheric and have aprofile described by equation (1) above. In various implementations ofthe lens illustrated in FIG. 7E, the surfaces can include higher orderaspheric terms such as upto 8^(th) order Zernike coefficients or higher.Various implementations of the lens illustrated in FIG. 7E can have athickness between about 1 mm and about 1.6 mm. The average MTF for theimplementation of a lens illustrated in FIG. 7E at a peripheral retinallocation at an eccentricity between about 7-degrees and about 13-degreescan be greater than 0.8 at a spatial frequency of 30 cycles/mm for bothtangential and sagittal foci.

Embodiments 6 & 7

The implementations of lenses discussed above can be implanted in theeye such that the distance between the pupil and the anterior surface ofthe lens is small. For example, the implementation of lenses disclosedabove can be implanted such that the distance between the pupil and theanterior surface of the lens is between 0.9 mm and 1.5 mm. However, itis also conceived that the implementations of the lens discussed abovecan be implanted as far back in the eye as possible. For example, insome implementations, the lens can be implanted such that it is still inthe capsular bag but the distance closer to the retina. In suchimplementations, the distance between the pupil and the anterior surfaceof the lens can be between distance between 1.5 mm and 3.2 mm. Theprofiles of the various surfaces would change as the distance betweenthe pupil and the lens changes. This is illustrated in FIGS. 7F and 7Gand discussed below. FIG. 7F shows a cross-section view of an embodimentof a moved symmetric IOL configured to provide improved vision at alocation of the peripheral retina and FIG. 7G shows a cross-section viewof an embodiment of a moved asymmetric IOL configured to provideimproved vision at a location of the peripheral retina.

A comparison of FIGS. 7C and 7F and a comparison of FIGS. 7D and 7Gillustrates that the curvatures of the surfaces change as the distancebetween the pupil and the retina is varied. The lens illustrated in FIG.7F has an average MTF greater than about 0.8 at a spatial frequency of30 cycles/mm at a peripheral retinal location at an eccentricity betweenabout 7-degrees and about 13-degrees for both tangential and sagittalfoci. The lens illustrated in FIG. 7G also has an average MTF greaterthan about 0.8 at a spatial frequency of 30 cycles/mm at a peripheralretinal location at an eccentricity between about 7-degrees and about13-degrees for both tangential and sagittal foci.

Embodiments 8-11

The implementations of lenses illustrated in FIGS. 7H-7K illustrateimplementations of a dual optic IOL whose surfaces are configured suchthat the light incident obliquely with respect to the optical axis isfocused at a peripheral retinal location with reduced errors. Suchlenses are also described in U.S. application Ser. No. ______, filedconcurrently herewith on Mar. 10, 2015, titled “DUAL-OPTIC INTRAOCULARLENS THAT IMPROVES OVERALL VISION WHERE THERE IS A LOCAL LOSS OF RETINALFUNCTION,” Attorney Docket No. AMOLNS.055A1, which is incorporatedherein by reference in its entirety. FIG. 7H shows a cross-section viewof an embodiment of a dual optic IOL configured to provide improvedvision at a location of the peripheral retina. FIG. 7I shows across-section view of an embodiment of a dual optic IOL configured toprovide improved vision at a location of the peripheral retina and atthe fovea. FIG. 7J shows a cross-section view of an embodiment of anaccommodating dual optic IOL configured to provide improved vision at alocation of the peripheral retina. FIG. 7K shows a cross-section view ofan embodiment of an accommodating dual optic IOL configured to provideimproved vision at a location of the peripheral retina and at the fovea.The surfaces of the lenses illustrated in FIGS. 7H-7K can be aspheric orspherical. The lens illustrated in FIGS. 7H-7K have an average MTFgreater than about 0.8 at a spatial frequency of 30 cycles/mm at aperipheral retinal location at an eccentricity between about 7-degreesand about 13-degrees for both tangential and sagittal foci. One or bothof the viewing elements of the dual optic IOL can include redirectingelements similar to the prismatic features and/or diffractive featuresdescribed herein. The redirecting elements can be configured to redirectlight incident on the eye along the optical axis and/or at an angle tothe optical axis to one or more locations on the retina.

Embodiments 12 & 13

The implementations of lenses illustrated in FIGS. 7M and 7N illustrateimplementations of a piggyback IOL that can be provided in addition toan existing lens (natural lens or a standard IOL) for patients with AMD.Such lenses are also described in U.S. application Ser. No. ______,filed concurrently herewith on Mar. 10, 2015, titled “PIGGYBACKINTRAOCULAR LENS THAT IMPROVES OVERALL VISION WHERE THERE IS A LOCALLOSS OF RETINAL FUNCTION,” Attorney Docket No. AMOLNS.055A3, which isincorporated herein by reference in its entirety. FIG. 7L shows across-section view of an embodiment of a symmetric piggyback IOLconfigured to provide improved vision at a location of the peripheralretina and at the fovea. FIG. 7M shows a cross-section view of anembodiment of an asymmetric piggyback IOL configured to provide improvedvision at a location of the peripheral retina and at the fovea. Thepiggyback IOLs can be configured to provide optical power in the rangebetween about −10.0 Diopter and +10.0 Diopter. The piggyback IOLs canhave a thickness between about 0.3 mm and about 1.0 mm such that theycan be inserted between the iris and an existing lens.

The surfaces of the lenses illustrated in FIGS. 7M and 7N can beaspheric or spherical. The lens illustrated in FIGS. 7M & 7N have anaverage MTF greater than about 0.7 at a spatial frequency of 30cycles/mm at a peripheral retinal location at an eccentricity betweenabout 7-degrees and about 13-degrees for both tangential and sagittalfoci. The implementation of piggyback lenses disclosed herein caninclude redirecting elements similar to the prismatic features and/ordiffractive features described herein. The redirecting elements can beconfigured to redirect light incident on the eye along the optical axisand/or at an angle to the optical axis to one or more locations on theretina.

The tables below summarize the optical performance of variousembodiments of lenses discussed above. The optical performance ischaracterized using a figure of merit such as an average MTF at aspatial frequency of 30 cycles/mm at different locations in theperipheral retina at an eccentricity between 7-13 degrees. Table 1provides the optical performance of the different lenses for a largepatch configuration. Without any loss of generality, a large patchconfiguration refers to configuration when the isoplantic patch islarge. In other words, there are a large range of angles (patch) ofincidence that are focused at corresponding retinal locations in a smallarea such that any individual point of the image is sharply focused.Table 2 provides the optical performance of the different lenses forreading.

TABLE 1 Optical performance for a large patch configuration MTF at 30Figure of Foveal MTF Symmetrical cycles/mm, merit large Acceptable at100 figure of eccentricity Design patch foveal cyces/mm Symmetricalmerit 5/15 deg Standard 0.70 X 0.76 X 0.67 0.86/0.42 Toric (1 D) 0.800.24 0.58 0.68/0.60 Enhanced Toric 0.90 0.25 0.58 0.63/0.36 Doubleasphere 0.87 X 0.74 X 0.75 0.87/0.45 Zernike anterior, 0.90 0.19 0.550.66/0.54 standard posterior Thick asphere 0.89 X 0.56 X 0.91 0.89/0.59Moved asphere 0.87 X 0.73 X 0.88 0.91/0.49 Moved asymmetric 0.94 0.190.74 0.82/0.74 Zernike Dual optics 0.92 0.07 X 0.94 0.81/0.65 Dualoptics 0.89 X 0.77 X 0.90 0.92/0.55 with good foveal Dual optics 0.89 X0.61 X 0.90 0.88/0.55 accommodating Dual optics 0.88 X 0.77 X 0.890.92/0.55 accommodating with good foveal Piggyback 0.90 0.19 0.630.76/0.58 asymmetric Piggyback 0.74 0.39 X 0.71 0.83/0.31 symmetric

TABLE 2 Optical performance for lenses configured for reading FigureAccept- Foveal MTF Sym- Figure of of merit able at 100 met- merit forDesign reading foveal cyces/mm rical large patch Standard 0.41 x 0.76 X0.70 Toric (1 D) 0.43 0.34 0.79 Enhanced Toric 0.44 0.22 0.83 Doubleasphere 0.58 X 0.44 x 0.82 Zernike 0.54 0.14 0.81 anterior, standardposterior Thick asphere 0.86 0 X 0.83 Moved asphere 0.74 0.30 X 0.82Moved 0.84 0.30 0.87 asymmetric Zernike Dual optics 0.87 x 0.73 X 0.84Dual optics 0.75 0.76 X 0.88 with good foveal Dual optics 0.81 0.14 0.82accommodatingIntraocular Lens with Two Zones

As discussed above, patients suffering from loss of central vision dueto AMD or retinal scotoma can benefit from ophthalmic solutions thatdeflect incident light to a preferred peripheral retinal location awayfrom the fovea. Embodiments discussed herein can deflect incident lightto a preferred peripheral retinal location away from the fovea andadditionally correct optical errors at the preferred retinal location.Various embodiments described herein include ophthalmic solutions thatare configured to focus a first portion of the incident light at a firstpreferred location of the retina (e.g., fovea 260) and a second portionof the incident light at a second preferred location of the retina(e.g., PRL 290). Such ophthalmic solutions are described below withreference to FIG. 8.

FIG. 8 illustrates an example intraocular lens 800 having two zones 805,810 with different optical properties. The IOL 800 can be configured toimprove or optimize both far vision and near vision, and to do so indifferent ways. The IOL 800 advantageously can improve overall visionwhere there is a loss of central vision by providing a magnified imageat the PRL for near vision and an image at the retina that issubstantially undeflected and unmagnified for far vision. In someembodiments, the near vision improving zone can redirect an image to thePRL without providing any additional magnification. In some embodiments,the far vision zone can redirect an image to a far-vision PRL, where thefar-vision PRL may be different from the near-vision PRL. It is to beunderstood, then, that the intraocular lens 800 may have more than twozones where each zone redirects images to a different PRL. In suchcases, the zones of the intraocular lens can have different, similar, oridentical optical powers, and the added magnification of one or more ofthe zones can be 0. This multi-zone IOL may be advantageous where apatient uses different PRLs for different vision tasks or where thepatient lacks a stable PRL.

In some embodiments, the first zone 805 is configured to improve oroptimize near vision. The first zone 805 can be configured to redirectan optical axis to a PRL within an eye of a patient to improve nearvision which is adversely affected by a loss of central vision. In someembodiments, in addition to redirecting incident light to the PRL, thefirst zone 805 can have an optical power configured to magnify the imageat the PRL and to correct for the peripheral errors arising at theeccentricity of the PRL, where the magnification is relative to themagnification provided by the eye without the IOL 800. In someembodiments, the magnification of the image at the PRL can beaccomplished through a combination of the magnification of the firstzone 805 and a magnification provided by a spectacle lens or contactlens. The spectacle lens or contact lens may be used to magnify andfocus on the retina relatively distant objects. For example, the IOL 800with additional optical power may result in a patient holding objectsrelatively close to the eye so the image of the object is magnified andfocused on the retina. By accounting for the use of a spectacle lens orcontact lens, the IOL 800 with a magnifying zone can be configured tomagnify and focus on the retina objects that are relatively further fromthe patient.

The first zone 805 can be configured to deflect incident light onto thePRL using a number of techniques including, for example and withoutlimitation, prisms, diffraction gratings, tailored refractive surfaces,materials with varying indices of refraction, or any of the othertechniques, systems, and/or methods disclosed herein. For example, thefirst zone 805 can include a redirection element configured inaccordance with the description provided herein with reference to FIGS.11-22. As another example, the first zone 805 can include a diffractiongrating configured in accordance with the description provided hereinwith reference to FIG. 26. As another example, the first zone 805 caninclude a decentered GRIN lens configured in accordance with thedescription provided herein with reference to FIG. 23.

In some embodiments, the optical diameter of the first zone 805 is smallrelative to the diameter of the IOL 800 (e.g., at least about 1.5 mmand/or less than about 4.5 mm, or at least about 2 mm and/or less thanabout 3 mm, or less than about 2.5 mm). This advantageously can easedesign constraints of the IOL lens 400 because it can reduce thethickness of the lens. A thinner lens can be easier to implant and canhave less risk of complications. The small optical diameter may alsolimit the central thickness of the IOL 400 such that a solutionutilizing a prism may be appropriate.

In some embodiments, the second zone 810 is configured to improve oroptimize far vision. The second zone 810 can be configured to improve auser's contrast sensitivity here there is a loss of central vision bymaintaining or approximating the optical axis and magnification of thenatural lens. This may allow the user to utilize all 4 quadrants of thevisual field for far vision which is beneficial for orientation andmoving around. For instance, the second zone 810 can be configured tonot significantly deflect the optical axis of incident light and to notsignificantly magnify the image on the retina. Doing so may allow a userto process the visual context of a scene which reduces disorientationand reduces difficulty in moving around and identifying moving objects.

In FIG. 8, the first and second zones 805, 810 are respectivelyillustrated as circular and annular. However, the shapes of the firstand second zones 805, 810 can be any regular or irregular closed shapeconfigured to provide the visual characteristics to improve overallvision or contrast sensitivity where there is a loss of central vision.The second zone 810 can be configured to surround the first zone 805,and, in some embodiments, the second zone 810 can be configured toextend from the periphery of the first zone 805 to the periphery of theIOL 800. In some embodiments, the IOL 800 can include more than twozones. For example, a third zone can be included in the IOL 800 whichcan be configured to deflect incident light along a deflected opticalaxis (e.g., to the PRL or to another location on the retina such as asecondary PRL), to magnify the image on the retina, to correctaberrations, etc. In some embodiments, the first and second zones 805,810 can be adjacent to one another or separate regions on the IOL 800,where neither zone surrounds the other zone.

The separation or boundary between the first zone 805 and the secondzone 810 of the IOL 800 can be a physical discontinuity (e.g., asillustrated in FIG. 9), an optical discontinuity (e.g., differentindices of refraction), or both. In some embodiments, the first zone 805and second zone 810 are not separated by a discontinuity, physicaland/or optical, but are defined in terms of functionality where one ofthe zones deflects incident light and magnifies the image on the retinawhereas the other zone does not substantially deflect incident light ormagnify the image on the retina. In such cases, the transition betweenthe zones can be a smooth or substantially continuous change of physicaland/or optical properties.

The IOL 800 can be modified to provide the two zones 805, 810 and theirassociated properties, as set forth herein. An unmodified IOL can beprovided and altered so as to include the first and second zones 805,810. For example, a redirection element can be added to a portion of theIOL 800 to direct light along a deflected optical axis. As anotherexample, a portion of the anterior surface of the IOL 800, the posteriorsurface of the IOL 800, or both can be modified to provide the two zones805, 810. As another example, the refractive index of the first zone805, of the second zone 810, or of both zones can be modified using alaser treatment.

The IOL 800 with at least two zones can also be further modified toprovide additional benefits. For example, one or both zones 805, 810 canbe tailored to reduce or eliminate optical aberrations (e.g., sphericalaberration, astigmatism, coma, field distortion, chromatic aberration,etc.). As another example, the first zone 805 may be modified to includea bifocal lens to improve accommodation for a user.

The IOL 800 described herein with reference to FIG. 8 includes the firstzone 805 configured to improve or optimize near vision and the secondzone 810 configured to provide vision in all four quadrants of thevisual field to aid in orientation and moving around when using farvision. In some embodiments, the IOL 800 can be configured such that theroles of the first and second zones 805, 810 are reversed, e.g., thefirst zone 805 provides vision in all four quadrants of the visual fieldand the second zone 810 is configured to improve or optimize nearvision.

FIG. 9 illustrates an example intraocular lens 800 having two zones 805,810 with different optical powers. As illustrated, the first zone 805,or central zone “C”, has a physical discontinuity from the second zone810, or peripheral zone, which surrounds the central zone 805. Thecentral zone 805 is used for near vision and focuses incident light onthe PRL (e.g., along a deflected optical axis OA′) and magnifies theimage at the PRL (e.g., the magnification of the eye with the IOL 800relative to the magnification of the eye with its natural lens isgreater than 1, or M_(R)′>1). The peripheral zone 810 is used for farvision and directs incident light to the retina without substantialdeflection (e.g., maintains the optical axis OA of the eye with itsnatural lens) and without substantial magnification (e.g., themagnification of the eye with the IOL 800 relative to the magnificationof the eye with its natural lens is about 1, or M_(R)≈1).

The deflected optical axis OA′ can be configured to deviate from theoptical axis of the eye with its natural lens to intersect the retina atthe PRL. The undeflected optical axis OA can be configured tosubstantially align with the optical axis of the natural lens (e.g., theoptical axis that intersects the fovea at the retina or which representsan eccentricity of about 0 degrees). The relative magnification of thecentral zone M_(R)′ can be configured to magnify the image at the PRLrelative to a magnification of the eye with its natural lens M or therelative magnification of the peripheral zone, M_(R). The relativemagnification of the peripheral zone M_(R) can be configured to besubstantially the same as the magnification provided by the naturallens. In some embodiments, both M_(R) and M_(R)′ can be greater than 1.In some embodiments, M_(R)′ can be greater than about 1.75 and/or lessthan or equal to about 6 (e.g., where M_(R)′=1+F/4 and F is the addedpower in diopters).

In some embodiments, the power of the central zone 805 can be greaterthan an optical power of the peripheral zone 810. For example, theoptical power of the central zone 805 can be about 10 diopters higher orat least 3 diopters higher and/or less than 20 diopters higher than theoptical power of the peripheral zone 810. In such a configuration, thenear image is blurred for far vision such that the blurred near image isa limited impediment to far vision. In addition, the higher power fornear vision can enable the user to see a sharper image up close (e.g.,improving a user's ability to read).

FIG. 10 illustrates an example method 600 for improving contrastsensitivity or overall vision where there is a loss of central visionusing an intraocular lens with two zones. The IOL can be similar to theIOL described herein with reference to FIGS. 8 and 9, where there is afirst zone configured for near vision and a second zone configured forfar vision.

In block 605, a deflected optical axis is determined which intersects aPRL of a patient at the retina. The deflected optical axis can beconsidered to be deflected from the natural optical axis 280 of the eye,as illustrated in FIG. 1. The deflected optical axis can be configuredto intersect the patient's retina at the PRL such that light directedalong the deflected optical axis and focused onto the patient's PRL canbe resolved by the patient instead of being directed along the naturaloptical axis and focused onto a damaged portion of the retina. The PRLcan be one of a plurality of potential PRLs, some or all of which may beadvantageously used by a patient.

In some embodiments, block 605 includes determining the PRL (orplurality of candidate PRLs) for a patient. The PRL can be determinedusing analytical systems and methods designed to assess retinalsensitivity and/or retinal areas for fixation. Such systems and methodscan include, for example and without limitation, providing a patientwith stimuli and imaging the patient's retina to assess topographicretinal sensitivity and locations of preferred retinal loci. Forexample, a microperimeter can be used to determine a patient's PRL bypresenting a dynamic stimulus on a screen and imaging the retina with aninfrared camera. As another example, a retinal area used for fixationcan be assessed using a laser ophthalmoscope (e.g., an infrared eyetracker) which can be used to determine discrete retinal areas forfixation for various positions of gaze.

In some embodiments, a diagnostics system can be used to determine thePRL. The system can be configured to bypass the optics of the patient.In some instances, optical errors induced by a patient's optics cancause the patient to select a non-optimal PRL or a PRL which does notexhibit benefits of another PRL, e.g., where a patient selects anoptically superior but neurally inferior region for the PRL. This can beadvantageous because this would allow the identification of a PRL which,after application of corrective optics (e.g. the IOLs described herein),would provide superior performance compared to a PRL selected utilizinga method which includes using the patient's optics because thecorrective optics reduce or eliminate the optical errors which are atleast a partial cause for a patient selecting a sub-optimal PRL.

In some embodiments, multiple candidate locations for the PRL can bedetermined. The preferred or optimal PRL, or the preferred or optimalset of PRLs, can be based at least upon several factors including, forexample and without limitation, a patient's ability to fixate a pointtarget, distinguish detail, and/or read; aberrations arising fromredirecting images to the candidate PRL; proximity to the damagedportion of the retina; retinal sensitivity at the candidate location;and the like. The preferred or optimal PRL can depend on the visual taskbeing performed. For example, a patient can have a first PRL forreading, a second PRL when navigating, and a third PRL when talking anddoing facial recognition, etc. Accordingly, multiple PRLs may beappropriate and an IOL can be configured to redirect incident light tothe appropriate PRLs using multiple zones, as described herein. Forexample, although the method 600 describes providing an IOL with twozones, the method 600 can be expanded to include providing an IOL withgreater than two zones, with one or more zones redirecting light to adesignated PRL, where the zone can be configured to have additionaloptical power or no additional optical power. In some embodiments, aplurality of PRLs can be selected or used for a patient to accomplishone or more visual tasks.

In block 610, the IOL is configured to include a PRL zone whichredirects incident light along the deflected optical axis determined inblock 605. The PRL zone can be used to improve near vision for thepatient suffering from central vision loss, e.g., to improve visionassociated with one or more visual tasks. The IOL can be configured toinclude an optical and/or physical discontinuity such that the firstzone deflects incident light along the deflected optical axis. The IOLcan be configured to include a redirection element (e.g., prisms,diffraction gratings, and/or any other system or method disclosed ordescribed herein) on an anterior surface of the IOL, on a posteriorsurface of the IOL, and/or the anterior and/or posterior surfaces of theIOL can be modified to deflect the optical axis. In some embodiments,the deflecting element can be designed to correct for the peripheralrefractive errors at the PRL location. These errors can be determined atthe time of PRL determination. The IOL can be configured to redirect theincident light by altering the index of refraction of the first zone(e.g., using a laser treatment) so that light incident on the first zoneis deflected along the deflected optical axis. The IOL can be configuredto include a combination of features (e.g., redirection elements,tailored indices of refraction, etc.) to achieve the result ofdeflecting the optical axis.

In block 612, the procedure is repeated if there are multiple PRLs to beused in the IOL. For each PRL, a deflected optical axis is determined inblock 605 and a PRL zone in the IOL is configured to direct images tothe corresponding PRL. In this way, the IOL can be configured to improveoverall vision by directing images to a plurality of PRL locations.

In block 615, the IOL is configured to include a far vision zone whichdirects incident light along an undeflected optical axis (e.g., theoptical axis of the patient's eye with its natural lens). The far visionzone can be configured to provide far vision for the patient. Theundeflected optical axis can be advantageous for far vision because itcan direct light from a scene to all four quadrants of the patient'sretina, providing context for the patient useful for orientation andmoving around. Substantially deflecting the light may comprise vision inthe part of the visual field opposite the deflection, reducing apatient's far-vision capabilities.

The far vision zone can be configured to surround one or more of the PRLzones where the PRL zones are located in a central portion of the IOL(e.g., as concentric rings or adjacent regions). The far vision zone canbe configured to be located in a central portion of the IOL, in whichcase the PRL zones can be configured to surround the far vision zone(e.g., as concentric rings, segmented regions around the far visionzone, or a combination of these configurations).

In block 620, an optical power of one or more of the PRL zones isadjusted to be greater than a power of the far vision zone. The opticalpower of at least one PRL zone can be configured to provide a relativemagnification of an image at the corresponding PRL, where themagnification of the image is relative to the magnification provided bythe natural lens of the patient. In some embodiments, the depth of focusof the far vision zone can be extended through, for example and withoutlimitation, refractive or diffractive principles generally applicablefor IOL design. This may be advantageous because the extended depth offocus in the on-axis image may provide a greater tolerance to refractiveerrors (e.g., relative to deflected images) and allow for intermediatevision for the patient. Examples of such techniques are disclosed inU.S. patent application Ser. No. 12/771,550 filed Apr. 30, 2010, whichis incorporated herein by reference in its entirety. The optical powerof the second zone can be configured to provide little or nomagnification relative to the natural lens of the patient. In someembodiments, the optical power of the first zone can be about 10diopters or at least about 3 diopters and/or less than or equal to about20 diopters greater than the optical power of the second zone. Themagnification provided by the first zone can advantageously improve nearvision without significantly compromising far vision because for farvision the near image is blurred, and for near vision the near image ismagnified to compensate for reduced retinal sensitivity at the PRL.

Intraocular Lens with Tailored Redirection Element

When using a PRL to compensate for central vision loss, a patient mayredirect their eyes or head so that the object to be imaged is in alocation that is imaged onto the PRL. The oblique incidence of the lightfrom the object on the eye can induce optical aberrations such as comaor astigmatism at the PRL. Similarly, some optical elements which simplyredirect light from an oblique incidence to the PRL may induceequivalent or similar aberrations, even where the patient no longerredirects their eyes and/or head. It would be advantageous, then, for apatient suffering from central vision loss to incorporate into thepatient's eye an optical element configured to deflect incident rays sothat they form a sharp image on the PRL instead of at the fovea.

In some embodiments, an IOL can be configured to include a redirectionelement (e.g., a prism-like shape or other optical element with atailored slope profile) at a surface of the IOL (or elsewhere in theeye) to shift the position of an image from the fovea to the PRL, asdescribed herein with reference to FIG. 4A-2. When using a typical prismto perform this redirection, optical aberrations may arise due at leastin part to the high vergence of the incident rays (which occur due tothe focusing power of the cornea). A Fresnel prism may be used to shiftthe image positions and to reduce the thickness of the prism used in theIOL. However, even a very thin Fresnel prism, in combination with theincoming rays having a high vergence, will still induce opticalaberrations of a magnitude that is similar to what a patient will getwhen fixating to the PRL by themselves. Accordingly, some embodimentsprovide for a redirection element with a tailored slope profile, or atailored redirection element, which can be configured to achieve thedesired shift in image position while providing good optical quality(e.g., without losing the optical quality of the unshifted image,reducing or eliminating aberrations, etc.). The tailored redirectionelement can include a surface with a slope which varies as a function ofsurface position, wherein the slope profile is calculated numerically oranalytically based at least in part on the desired shift in imageposition and the slope profile is configured to reduce or eliminateaberrations arising from the shift in image position.

To illustrate effects of shifting an image from the fovea, simulationshave been performed on an eye including various redirection elements. Inthe following figures, the PRL has been simulated as being 10 degreesfrom the fovea inside the eye. Other angles are possible, and resultswould be similar for other such angles. For each of FIGS. 11-13 and18-22, the left plot shows ray convergence (rays 705) before hitting thelast surface of the IOL 725, ray convergence (rays 710) after the lastsurface of the redirection element 720, and the focus at the PRL (thespoked circle 715), and the right plot shows the area around the PRL715, which represents a zoomed-in view of the left plot. The axesrespectively represent the surface profile of the lens in millimeters(x-axis 702) and the pupil position at the lens in millimeters (y-axis704), that is the axes represent the position in the eye with the originbeing the vertex of the posterior lens surface, and moving along thex-axis represents moving along the optical axis from the pupil to theretina. Listed above each zoomed-in view (the plot on the right in thefigures) is the mean absolute transversal error at the focus and themean ray distance to the PRL (both given in millimeters). The meanabsolute transversal error is defined as the average absolutetransversal distance (e.g., the absolute value of the distance along they-axis) from the rays to the PRL at the x position corresponding to thePRL location, and smaller values are better because it indicates theresulting image is of a higher optical quality (e.g., it is less blurry)and smaller objects can be resolved. For example, if all raysintersected the PRL then the mean absolute transversal error would be 0because at the x position, all rays would be 0 mm from the PRL along they-axis. The mean ray distance to the PRL is defined as the averagedistance to the PRL (e.g., the distance from a ray to the PRL along they-axis at the x position of the PRL) for all of the rays, and smallervalues are better because it indicates a smaller systematic misplacementof the intended focal position or that, on average, the center of thepoint spread function is closer to the PRL. For example, if the rays areevenly spread about the PRL, then the mean ray distance would be 0 mm,indicating no misplacement of the focal position.

The first plot, illustrated in FIG. 11, shows the effects of using asimple prism with a maximum thickness of 42 mm. The profile of the prismis shown as line 720, whereas the posterior surface of the IOL is shownas line 725. In FIG. 11, all of the optical power of the IOL is in thefirst, anterior surface (e.g., the posterior surface is flat, as shown).In this case, the mean absolute transversal error at the focus is about0.23 mm and the mean ray distance to the PRL is about 0.24 mm.

Switching to a Fresnel prism 720 with a maximum height of 0.5 mmimproves the optical quality at the PRL 715, as illustrated in the plotsshown in FIG. 12. As in FIG. 11, the optical power of the IOL isconfigured to be in the first, anterior surface. In this case, the meanabsolute transversal error at the focus is about 0.053 mm and the meanray distance to the PRL 715 is about 0.053 mm, representing asignificant improvement over the simple prism implementation of FIG. 11.However, these errors may still be unacceptably high due to the inducedoptical aberrations. For example, a mean error of about 0.05 mmrepresents a blurring equivalent with log MAR of about 1.0.

It may be advantageous, instead, to provide a general analytical methodwhich produces a slope profile tailored to produce a sharp image (e.g.,with limited optical aberrations) at the PRL and which accepts as input,for example and without limitation, the PRL location, retinal shape,axial length, corneal power, predicted IOL position, and power ofposterior lens surface. In some embodiments, a tailored redirectionelement can be designed having a tailored slope profile based at leastin part on such a general analytical method.

The general analytical method can provide a tailored or customized slopeprofile of a redirection element which achieves the desired shift inimage position while maintaining good optical quality. The generalanalytical method can be used to generate an IOL with a redirectionelement tailored to redirect an image to the PRL and to reduce opticalaberrations (e.g., coma) associated with such a shift in image position.The inputs of the general analytical method can include the distancefrom the lens vertex to the original focus (l), the index of refractionof the IOL (n_(l)), the index of refraction of the aqueous environment(n_(aq)), the angle inside the eye to the PRL relative to the backvertex of the IOL (a_(p)), the radial position of the IOL (x), and/orthe posterior radius of curvature of the IOL (r). A first step in thegeneral analytical method can include analytically calculating the slopeat each point on the posterior surface of the IOL which would directincident light rays to the PRL. Using Snell's law, an analyticalexpression can be found for the slope as a function of radial position,x, is given by Equation (3) below:

$\begin{matrix}{{{{slope}(x)} = {- {\cos^{- 1}\left( \frac{{n_{aq}\cos \; \alpha} - {n_{l}\cos \; \beta}}{\sqrt{n_{aq}^{2} + n_{l}^{2} - {2\; n_{aq}n_{l}\sin \; \alpha \; \sin \; \beta} - {2\; n_{aq}n_{l}\cos \; \alpha \; \cos \; \beta}}} \right)}}}{where}{\alpha = {\tan^{- 1}\left( \frac{{l\; \sin \; a_{p}} - x}{{l\; \cos \; a_{p}} - r - \sqrt{r^{2} - x^{2}}} \right)}}{and}{\beta = {\sin^{- 1}\left( {\frac{n_{aq}}{n_{l}}{\sin \left( {{\tan^{- 1}\left( \frac{- x}{l - r - \sqrt{r^{2} - x^{2}}} \right)} + {\sin^{- 1}\left( \frac{x}{r} \right)}} \right)}} \right)}}} & (3)\end{matrix}$

The analytical solution given as Equation (3) represents the slope as afunction of position for a redirection element which can be included asan additional refractive surface positioned on or after a posterior IOLsurface where the posterior IOL surface refracts the light before theredirection element. To derive the analytical solution, the initial rayis treated as converging toward the retina where the initial ray, I, isgiven by the equation tan⁻¹(−x/l). Then it is recalculated how it wouldbe if the power of the back optical surface were not used (as the slopeis being changed), giving the angle of the ray at every point inside theIOL. The slope of the surface of the IOL, s, is given by tan⁻¹(x/r) andthe refraction at the first surface is given by sin⁻¹((n_(l)/n_(aq))sin[l+s]) The angle of the ray is recalculated so that it is towards theoptical axis of the eye, where the angle relative to the optical axis,o, is given by r+s. The desired slope for every ray inside the IOL iscalculated to hit the PRL where the desired slope, d, is given bytan⁻¹((l sin a_(p)−x)/(l cos a_(p)+r−sqrt(r²−x²))). Snell's law is thenused with the slope profile, p, as the unknown with the incident anddesired ray slopes known. A solution is found for p in the equationsin(d−p)=n_(l) sin(o−p). The solution, p, can be given as:

$- {{\cos^{- 1}\left( \frac{{n_{l}\cos \; o} - {n_{aq}\cos \; d}}{\sqrt{n_{aq}^{2} + n_{l}^{2} - {2n_{aq}n_{l}\sin \; d\; \sin \; o} - {2\; n_{aq}n_{l}\cos \; d\; \cos \; o}}} \right)}.}$

FIGS. 13-15 illustrate examples of slope profiles 1005 calculated usingthe above expression, where the PRL is located respectively at 5degrees, 7.5 degrees, and 10 degrees from the fovea. The x-axis 1002represents the pupil position in millimeters and the y-axis 1002represents the slope of the redirection element in degrees. A simpleprism 1010 with a constant slope is illustrated in each figure forcomparison. FIG. 16 is equivalent to FIG. 15 except that it adds a slopeprofile 0715 for a segmented redirection element where the slope in asegment is constant across that zone and where the slope in that zone isbased on the tailored slope profile 1005. At every location in thesegmented redirection element, the slope is constant (e.g., within azone, the slope is constant), but the slope is different from zone tozone. As is evident from the slope profiles in FIGS. 14-17, the slopeprofile does not necessarily monotonically increase or decrease as itdepends on multiple factors. In addition, the difference in slope fromone portion of the redirection element to another can be substantial(e.g., 10 degrees) for typical PRL locations, indices of refraction,and/or incident vergence profiles.

Applying the slope profile from FIG. 16 to a redirection element canimprove the image quality at the PRL 715, as shown in FIG. 17. Theanalytically tailored redirection element of FIG. 17 can have differentzones, wherein the slope within each zone varies according to the slopeprofile calculated using the analytical expression above. Theredirection element with the tailored slope profile is incorporated ontothe posterior surface 725 of the IOL, the posterior surface 725 havingsome optical power. In this case, the mean absolute transversal error atthe focus is about 0.020 mm and the mean ray distance to the PRL 715 isabout 0.042 mm, representing an improvement over the Fresnel prismimplementation of FIG. 12. However, the first step of the generalanalytical method did not take the thickness of the redirection elementinto account. The results can be improved where these factors areaccounted for in the design of the slope profile.

Accordingly, the second step of the general analytical method is toperform an iterative procedure to adjust the slope profile of thesurface of the redirection element. This can be accomplished bybeginning at an initial point in a Fresnel zone, updating the slopeprofile, and then integrating to get the surface shape. Beginning withthe analytical expression for the slope profile (e.g., Equation (3)),the height is calculated at each part on the IOL. This can be done in asingle dimension, the dimension of redirection. For each part of theIOL, the actual ray is calculated and compared to the desired ray (e.g.,the ray that would exactly intersect the PRL). Where there is adifference between the actual ray and the desired ray, the slope isadjusted to get the desired ray. Next, the slope profile isrecalculated. The recalculated slope profile provides a better imagewhich may be improved with additional iterations. The iterativeprocedure can be stopped when one or more parameters indicative of imagequality are within a designated, targeted, or desired range. Thisiterative procedure is referred to in FIG. 21, and specifically referredto in block 1920. In this way, image quality at the PRL can be improvedor optimized via a gradual adjustment of the slopes provided by theanalytical expression described herein above. FIG. 18 illustrates imagequality at the PRL when the iterative procedure is performed on theredirection element of FIG. 17. In this case, the mean absolutetransversal error at the focus is about 0.0047 mm and the mean raydistance to the PRL 715 is about 0.0048 mm, far superior to the opticalquality provided by Fresnel prisms with a constant slope, as exemplifiedin FIG. 12.

In some embodiments, the general analytical method can be applied to aFresnel prism that is thicker and that has fewer Fresnel zones than thepreviously shown prisms. One such example is illustrated in FIGS. 21 and22, which shows Fresnel prisms with a maximum thickness of 2 mm andslope profiles respectively configured as those in FIGS. 18, and 19. Inparticular, the redirection element in FIG. 19 represents a tailoredredirection element with a slope that varies according to the analyticalexpression described herein above. The redirection element in FIG. 20represents a redirection element with a tailored slope profile that hasbeen modified according to the iterative procedure of the secondoperation of the general analytical method, described herein above. Themean absolute transversal errors at the focus of FIGS. 21-22 arerespectively about 0.082 mm, and 0.013 mm. The mean ray distance to thePRL 715 of FIGS. 21-22 are respectively about 0.16 mm, and 0.013 mm.

The tailored redirection elements incorporating the slope profilesdetermined using the above described general analytical methoddemonstrate improved image quality at large and small eccentricities,when compared to simple prisms and simple Fresnel prisms. Based at leastin part on the density of retinal ganglion cells being higher at morecentral parts of the retina, the improved image quality provided by thetailored redirection elements can be useful at substantially alleccentricities within the eye (e.g., from a few degrees to about 30degrees).

In some embodiments, the general analytical method can be based on anabsolute value of the deflection angle requested or desired. Whenincorporated into a patient's eye, then, the IOL can be rotated so thatthe deflected optical axis intersects the retina at the PRL (e.g., wherethe relative position of the PRL is nasal, temporal, inferior, superior,or a combination of these). In some embodiments, the general analyticalmethod can be applied to correcting small deflections or eccentricitiesin LASIK nomograms directed to treating patients with central visionloss (e.g, due to AMD).

FIG. 21 illustrates an example method 1900 for providing an IOL to focusimages onto a PRL. The IOL can be configured to include a redirectionelement that redirects incident light to the PRL. The redirectionelement can be incorporated onto the IOL or at any other suitablelocation to accomplish the redirection in cooperation with the IOL. Themethod 1900 can be configured to provide focused light at the PRL whilereducing or minimizing aberrations at the PRL relative to simplyredirecting light to the PRL using a typical prism or equivalent design.The method 1900 can include performing the operations of the generalanalytical method described herein above.

In block 1905, a deflected optical axis is determined which intersects aPRL of a patient at the retina. The deflected optical axis can beconsidered to be deflected from the natural optical axis 280 of the eye,as illustrated in FIG. 1. The deflected optical axis can be configuredto intersect the patient's retina at the PRL such that light directedalong the deflected optical axis and focused onto the patient's PRL canbe resolved by the patient instead of being directed along the naturaloptical axis and focused onto a damaged portion of the retina.

As described herein with reference to FIG. 10, and particularly withreference to block 605, block 1905 can include determining the PRL of apatient. The techniques, systems, methods, and considerations describedherein above also apply here.

In operational block 1910, a slope is determined for points on a surfaceof the IOL, wherein the slope at each of these points is configured toredirect light to the PRL and/or along the deflected optical axisdetermined in block 1905. The determined slope can be applied to aredirection element that is incorporated onto the IOL or implanted atany other suitable location in the eye. Based at least in part onSnell's law, the location of the PRL, and properties of the patient'seye, an analytical expression can be found for the slope as a functionof radial position. In some embodiments, the analytical expression isequivalent to the formula presented in Equation (3) above. Examples ofslope profiles 1005 calculated with Equation (3) are shown and describedherein above with reference to FIGS. 14-16. In some embodiments, theslope can be determined using a variety of input parameters including,for example and without limitation, the eccentricity (e.g., angle), theaxial eye length and the radius of curvature of the retina (e.g., theeye length to the PRL), the IOL position, the power of the cornea, orthe like. These and like input parameters can be used to determineoptical errors, e.g., in block 1915, and/or in the iterative procedureto reduce the optical errors in block 1920.

Returning to FIG. 21, in operational block 1915, optical errors aredetermined based on the slope profiles calculated in block 1910. Theoptical errors can include, for example and without limitation,astigmatism, coma, spherical aberrations, field curvature, etc. Theoptical errors can include the mean absolute transversal errors at thefocus and/or the mean ray distance to the PRL.

In operational block 1920, an iterative procedure is performed to adjustthe slope profile. In some embodiments, the slope profile can be appliedto a segmented redirection element, where the slope in each segmentcorresponds to the slope profile calculated for that surface position.The iterative procedure can be configured to account for the effects ofthe thickness of the redirection element incorporating the determinedslope profile. The iterative procedure can be configured to reduce theoptical errors determined in block 1915. The iterative procedureincludes beginning at an initial point in a zone, updating the slopeprofile, and then integrating to get the surface shape. Beginning withthe analytical expression for the slope profile (e.g., Equation (3)which assumes a thickness of 0 for the redirection element), the heightis calculated at each part on the IOL. This represents a height relativeto the surface of the IOL, for example. To simplify this procedure, thiscan be done in the dimension of redirection (e.g., a single dimension).For each part of the IOL, the actual ray is calculated and compared tothe desired ray (e.g., the ray that would exactly intersect the PRL).The two rays may differ based at least in part on the thickness of theredirection element (which may be not initially accounted for in thesolution to the analytical problem described herein). Where there is adifference between the actual ray and the desired ray, the slope isadjusted to get the desired ray. Next, the slope profile is recalculated(e.g., the height above the surface of the IOL, or the thickness of theredirection element). The recalculated slope profile provides a betterimage which may be improved with additional iterations. The iterativeprocedure can be repeated until one or more parameters indicative ofimage quality are within a designated, targeted, or desired range.Simulated results of applying this iterative procedure to a tailoredredirection element incorporated onto a posterior surface of an IOL areshown in FIG. 18, demonstrating a significant improvement in focus atthe PRL relative to a redirection element which has not been tailoredaccording to the method 1900.

Ophthalmic Device with Decentered Gradient Refractive Index (GRIN)

As discussed above, patients suffering from AMD can benefit fromophthalmic solutions (e.g., IOLs, contact lenses, spectacles, etc.) thatcan deflect and focus light away from the fovea 260 at a PRL. Patientssuffering from retinal scotoma or at risk for retinal scotoma also haveregions of decreased visual acuity and/or contrast sensitivity in thecentral visual field and can also benefit from such ophthalmicsolutions. Ophthalmic devices including an optical component whoserefractive index varies gradually can be employed to deflect light awayfrom the fovea 260 to the PRL 290 and improve vision in patients withAMD or retinal scotoma. The refractive index can vary axially, radially,angular or spherically. In order to deflect incident light such that itis focused at the PRL 290 instead of the fovea 260, the variation of therefractive index profile of the optical component is asymmetric about anaxis of rotational symmetry of the ophthalmic device. FIG. 22illustrates an example of an asymmetric refractive index profile alongone meridian for an optical component that can be included in anophthalmic device that is capable of deflecting light away from thefovea 260 to the PRL 290. In FIG. 22, the axis of rotational symmetrypasses through the origin at r=0. The optical component has the maximumrefractive index n0 in a region that is offset from the origin r=0.Accordingly, the refractive index profile is decentered (or asymmetric)with respect to the axis of rotational symmetry. In various embodiments,the optical component can be a Gradient refractive-index (GRIN) optichaving a gradual variation of the refractive index of a material.

FIG. 23 illustrates an embodiment of an ophthalmic device 2100 includingan optical lens 2104 and an optical component 2105 with a GRIN profile.The optical component 2105 has a GRIN profile that is decentered aboutan axis 2102 of the ophthalmic device 2100. The GRIN profile can bedecentered perpendicular to (e.g., along the x-axis and/or along they-axis) the axis 2102. The axis 2102 can represent the axis along whichthe lens 2104 is rotationally symmetric. Accordingly, the opticalcomponent 2105 is capable of deflecting and focusing incident light awayfrom the fovea 260 at the PRL 290. The optical component 2105 can be aflat lens as shown in FIG. 23. In some embodiments, the opticalcomponent 2105 can include a SELFOC™ lens wherein the refractive indexvaries radially (e.g., in the x-y plane) and is offset and/or decenteredfrom the axis 2102. In certain embodiments, the optical component 2105is disposed on a proximal surface of the lens 2104, and more generallycan be the proximal-most focusing element in the eye. In variousembodiments, the GRIN profile can vary axially (e.g., along the z-axis)and be decentered with respect to the axis 2102. In various embodiments,the GRIN profile can vary radially (e.g., in the x-y plane) and bedecentered with respect to the axis 2102. In some embodiments, therefractive index profile can vary elliptically or sinusoidally along theaxis 2102. In some embodiments, the refractive index profile can taperedgradient along the axis 2102.

In some embodiments, the optical component 2105 can have a refractiveindex profile as given by the equation (4) below:

n(r′)=n ₀√{square root over (2−(r′/nr ₁)²)}  (4)

In various embodiments, the variable r′ can be given by the equation (5)below:

r′(z)=√{square root over (x ² +y ²+(z−sgc)²)}  (5)

The terms nr₁ and sgc are constants that can be selected to obtain adesired refractive index profile. The term sgc is a measure of the focallength of the ophthalmic device 2100.

FIG. 24 shows the optical output from the ophthalmic device 2100. Inparticular, FIG. 24 illustrates the calculated through focus modulationtransfer function (MTF) along the line of deflection for the ophthalmicdevice 2100 as a function of the focal position. The MTF can becalculated (or simulated) using an optical simulation program such as,for example, OSLO, ZEMAX, CODE V, etc. Curve 2205 shows the variation ofthe MTF with respect to the focal position for sagittal rays. Curve 2210shows the variation of the MTF with respect to the focal position fortangential rays. Curve 2215 is the maximum MTF achievable by theophthalmic device 2100. The theoretical maximum MTF can be calculated byray trace analysis using an optical simulation program such as, forexample, OSLO, ZEMAX, CODE V, etc. Curves 2205 and 2210 are obtained bysetting the value of nr₁ to 2 in equation (4) and the value of sgc to 17mm in equation (5), and decenter the GRIN profile by about 3 mmperpendicular to the optical axis 2102. In various implementations, theGRIN profile can be decentered such that the center of the GRIN profileis located towards an edge of the ophthalmic device 2100 along theradial direction. As observed from FIG. 24, the maximum MTF for bothsagittal and tangential rays occurs at a non-zero focal positionindicating that both for sagittal and tangential rays the MTF may befurther optimized. The optical output from the ophthalmic device 2100can be modified by selecting other values for the variables nr₁ and sgcin combination with selecting different parameters for the optical lens2404 and/or the optical component 2105 such as, for example, curvatureof the anterior and posterior surfaces of the lens 2404 and/or theoptical component 2105, spherical aberration, amount of and directionalong which the refractive index is decentered (e.g. along thex-direction or the y-direction or both), etc.

In some embodiments, the optical component 2105 can have a refractiveindex profile as given by the equation (6) below:

n ²(r)=n ₀ ²[1−(nr ₁ r)² +nr ₂(nr ₁ r)⁴ +nr ₃(nr ₁ r)⁶ +nr ₄(nr ₁r)⁸]  (6)

In various embodiments, the variable r can be given by the equation (7)below:

r=√{square root over (x ² +y ²)}  (7)

The terms nr₁, nr₂, nr₃, and nr₄ are constants that can be selected toobtain a desired refractive index profile. For example, in someembodiments, the term nr₁ can be equal to 0.12, the term nr₂ can beequal to 0.24 and the term nr₃ can be equal to −0.2, and nr4 can beequal to zero and the GRIN profile can be decentered perpendicular tothe axis 2102 by about 3 mm. The optical output may be further optimizedby modifying the values of nr1, nr2, nr3 and nr4 and the amount ofdecentration.

The ophthalmic device 2100 including the optical component 2105 with aGRIN profile can include a marking to indicate an orientation of theophthalmic device 2100 or a direction of the gradient of the refractiveindex of optical component 2105. The ophthalmic device 2100 can berotated to achieve a desired orientation and position of the markingwhen disposed with respect to the structures of the eye to ensure thatincident light is focused at the PRL 290.

In various embodiments, the optical lens 2104 can be an intraocular lensthat can provide base optical power and/or add power. The optical lens2104 can be an intraocular lens implanted in the eye, a spectacle lensor a contact lens. In such embodiments, the optical component 2105 canbe configured as a piggyback lens or as an add-on to the optical lens2104.

Ophthalmic Device with Diffraction Grating and Achromatic DiffractiveSurface

A diffraction grating can be used to direct light incident from a firstdirection along a second direction different from the first direction. Adiffraction grating includes a plurality of diffracting structures suchas a groove, a slit, a lenslet, etc. The second direction along whichthe incident light is diffracted depends on the spacing between theplurality of diffractive structures and the wavelength of light. FIG. 25illustrates an example implementation of a linear grating 2300. Thegrating 2300 comprises a substrate 2305 including a plurality ofdiffracting structures (e.g., 2307 a and 2307 b). The distance, ‘d’,between consecutive diffracting structures 2307 a and 2307 b is referredto as the grating period. Incident light beam represented by ray 2310that is incident from a direction that is at an angle α from a normal tothe substrate 2305 is diffracted into several outgoing light beams 2312a, 2312 b and 2312 c traveling in different directions that make anangle β₀, β₁, and θ⁻¹ respectively with the normal to the substrate2305. The different directions β₀, β₁, and β⁻¹ are determined from thegrating equation mλ=d(sin α+sin β_(m)), where m is an integer and isreferred to as the diffraction order. Accordingly, an ophthalmic deviceincluding a grating (e.g., grating 2300) can be used to deflect incidentlight away from the fovea 260 and focus it at the PRL 290. For example,light incident at normal incidence making an angle close to or equal tozero degrees with a normal to the substrate 2305 can be deflected by anangle between about 5-10 degrees, for example, an angle of 7.3 degreesor an angle of about 8.3 degrees by a diffraction grating having agrating period d between about 3 and 10 microns, for example, 4 micronor 6 micron, for diffraction order m=2.

FIG. 26 illustrates an embodiment of an ophthalmic device 2400 includingan optical lens 2404 and an embodiment of a diffraction grating 2405. Invarious embodiments, the diffraction grating 2405 can be a lineargrating. The diffraction grating 2405 preferably is configured to bedisposed as close to the retina as possible, e.g., on the posteriorsurface of the lens 2404 or adjacent to an anterior surface of theinside posterior layers of an evacuated capsular bag. The diffractiongrating 2405 includes a plurality of diffracting structures having agrating period, d, between about 1 micron and about 20 microns, forexample, the grating period, d, can be 4 micron or 6 micron. Theophthalmic device 2400 including the diffraction grating 2405 candeflect incident light by about 4-10 degrees, for example, 5.3 degrees,7.9 degrees or 8.3 degrees such that incident light is deflected awayfrom the fovea and focused at the PRL 290.

The ophthalmic device 2400 including the diffraction grating 2405 caninclude a marking to indicate an orientation of the ophthalmic device2400. The ophthalmic device 2400 can be rotated to achieve a desiredorientation and position of the marking when disposed with respect tothe structures of the eye to ensure that incident light is focused atthe PRL 290.

FIG. 27 shows the polychromatic optical output from an embodiment of theophthalmic device 2400 including a linear diffraction grating havinggrating period of 6 microns. The linear grating includes a diffractingstructure designed for a central wavelength (e.g., 550 nm) to deflectlight to the second diffraction order. In particular, FIG. 27illustrates the calculated modulation transfer function (MTF) for theophthalmic device 2400 as a function of spatial frequency at a preferredlocation of the peripheral retina. In various implementations, the PRLcan correspond to the position on the peripheral retina where incidentambient light is best focused by the ophthalmic device 2400. Curves 2505and 2510 shows the variation of the MTF for polychromatic light (e.g.,white light) incident at normal incidence making an angle close to orequal to zero degrees with a normal to the substrate 2305 that isdiffracted into the second order (m=2) for sagittal rays and tangentialrays. Curve 2515 is the theoretical maximum MTF (as calculated by raytrace analysis using an optical simulation program) achievable by theembodiment of the ophthalmic device 2400. When calculating curves 2505and 2510, the grating is configured to have a tilt of about 3 degrees.

The angle at which light is diffracted by a diffraction grating (e.g.,diffraction grating 2300) depends on the wavelength of incident light,diffraction order and grating period. Moreover, the fraction of lightdiffracted into any order, which is the efficiency of the grating inthat order, is not same for all wavelengths. Generally, the efficiencyof a grating can be adjusted by changing the geometry (e.g., facetangles, shape and/or depth) of the diffracting features 2312 a, 2312 band 2312 c. The operation of optimizing the grating efficiency bychanging the shape of the diffracting features is referred to asblazing. As observed from FIG. 27, different wavelengths of light arediffracted into the second order with different efficiencies such thatthe MTF for tangential rays drops below 0.2 as the spatial frequencyincreases beyond 12 cycles/mm. Since, the ophthalmic device 2400 isconfigured to be disposed with respect to the structures of the eye andused to view illuminated by or emitting light in the visible spectral,it is advantageous if all wavelengths in white light are diffracted in agrating order with substantially the same efficiency. In other words, itwould be advantageous if the MTF for both sagittal and tangential rayswhen deflected to the PRL 290 had a MTF above a threshold (e.g., MTFgreater than 0.2) for all wavelengths of light in the visible spectrum.

Including an achromatic optical component can advantageously increasethe efficiency for different wavelengths diffracted into a gratingorder. The achromatic optical component is designed to reduce theeffects of chromatic aberration. The achromatic optical component isconfigured such that the focal points for two different wavelengths(e.g., red and blue) are in the same plane. For instance, the achromaticoptical component is configured such that the focal points for twodifferent wavelengths (e.g., red and blue) coincide at the PRL 290. Theachromatic optical component can include an achromatic diffractivesurface, an achromatic lens, such as, for example, a Littrow doublet, aFraunhofer doublet, a Clark doublet, etc.

FIG. 28 shows the optical output from an embodiment of ophthalmic device2400 including a linear diffraction grating having grating period of 6microns and an achromatic diffractive surface. In particular, FIG. 28illustrates the calculated modulation transfer function (MTF) for theophthalmic device 2400 including a linear diffraction grating and anachromatic diffractive surface as a function of spatial frequency atbest focus position, i.e. at the location of the PRL. Curves 26050 and26100 shows the variation of the MTF for polychromatic light (e.g.,white light) incident at normal incidence making an angle close to orequal to zero degrees with a normal to the substrate 2305 that isdiffracted into the second order (m=2) for sagittal rays and tangentialrays. Curve 26150 is the theoretical maximum MTF (as calculated by raytrace analysis using an optical simulation program) achievable by theembodiment of the ophthalmic device 2400 including a linear diffractiongrating and an achromatic diffractive surface When calculating curves26050 and 26100, the grating is configured to have a tilt of about 3degrees.

A comparison of FIGS. 27 and 28 shows that the inclusion of theachromatic optical component can increase the efficiency with whichdifferent wavelengths are focused at the PRL 290 such that the MTF fortangential rays is greater than 0.2 for spatial frequencies up to 36cycles/mm indicating improved image quality at the PRL. The efficiencywith which different wavelengths are focused at the PRL 290 can befurther increased by including additional optical component such asfilters, by changing the shape of the diffracting features and/or bychanging other features of the ophthalmic device 2400 such as refractiveindex of the materials of the lens 2404 and/or the optical component2405, radius of curvatures for the anterior and posterior surfaces ofthe lens 2404 and/or the optical component 2405, shape factor of thelens 2404, asphericity of the lens 2404, etc.

In various embodiments, the optical lens 2104 can be an intraocular lensthat can provide base optical power and/or add power. The optical lens2104 can be an intraocular lens implanted in the eye, a spectacle lensor a contact lens. In such embodiments, the optical component 2105 canbe configured as a piggyback lens or as an add-on to the optical lens2104.

Example IOLs with Redirection Elements

In some embodiments, the redirection elements described herein (e.g.,tailored redirection elements, diffraction gratings, decentered GRINetc.) can be applied on top of an existing IOL, where it can be added,for example and without limitation, using a ring structure; as aseparate, additional surface; put directly on top of a previous IOL; orthe like. Such a configuration could allow a person who had previouslyundergone cataract surgery to benefit from the redirection element ifthe person later loses central vision capabilities (e.g., due to AMD).

In some embodiments, the redirection elements described herein (e.g.,tailored redirection elements, diffraction gratings, decentered GRINlenses, etc.) can utilize materials of a higher index of refraction thanthe IOL into which they are incorporated. This may enable theredirection elements to be made even smaller (e.g., having a smallerthickness) which can reduce optical aberrations.

In some embodiments, the redirection elements described herein (e.g.,tailored redirection elements, diffraction gratings, decentered GRINlenses, etc.) can cover a portion of the IOL (e.g., at least about 1.5mm and/or less than about 4.5 mm in diameter, or at least about 2 mmand/or less than about 3 mm, or about 2.5 mm). Such a configuration canbe advantageous for haptics, insertion, manufacturing, leaving parts ofthe visual field undeflected (e.g., as with the dual-zone IOL describedherein), allowing use of retinal locations that are not at the PRL, etc.

In some embodiments, the redirection elements described herein (e.g.,tailored redirection elements, diffraction gratings, decentered GRINlenses, etc.) can be incorporated into the IOL on multiple surfaces(e.g., the anterior and/or posterior surfaces). It may be advantageousto position the redirection element on the posterior surface of the IOLto improve or optimize image quality. However, if physical constraintslimit placement options, the redirection element can be placed at allother available locations where implants can typically be positioned.

In some embodiments, an IOL can be configured to include a plurality ofredirection elements, such as the tailored redirection elements or anyof the other described redirection elements described herein, toredirect light to a corresponding plurality of PRLs. For example, afirst redirection element can be configured to redirect incident lightto a first PRL and a second redirection element can be configured toredirect incident light to a second PRL.

In some embodiments, the redirection elements described herein, e.g.,the tailored redirection element, can be implanted bilaterally torestore binocular vision. The redirection of each eye can be calculated(e.g., by finding a PRL for each eye) and tailored redirection elementscan be implanted in each eye to shift the positions of the images ofeach eye to their respective PRLs. This can allow a patient to lookstraight ahead and have the image at the PRL of both eyes, allowing thepatient to utilize binocular vision which is typically lost in patientssuffering from central vision loss.

Example IOL Design System

FIG. 29 illustrates a block diagram of an example IOL design system27000 for determining properties of an intraocular lens configured toimprove vision at a peripheral retinal location. The IOL design system27000 includes a controller 27050 and a computer readable memory 27100coupled to the controller 27050. The computer readable memory 27100 caninclude stored sequences of instructions which, when executed by thecontroller 27050, cause the IOL design system 27000 to perform certainfunctions or execute certain modules. For example, a PRL location module27150 can be executed that is configured to determine a location of oneor more PRLs for a particular patient. As another example, a deflectionmodule 27200 can be executed that is configured to determine a deflectedoptical axis which intersects the determined PRL location at the retina.As another example, an IOL modification module 27250 can be executedthat is configured to determine properties of the IOL which woulddeflect at least a portion of incident light along the determineddeflected optical axis to the determined PRL. As another example, an IOLselection module 27270 can be executed that is configured to select anappropriate or candidate IOL provided one or more selection parametersincluding, for example and without limitation, PRL location and apatient's biometric data.

The PRL location module 27150 can be configured to determine one or morecandidate PRL locations using analytical systems and methods designed toassess retinal sensitivity and/or retinal areas for fixation. Forexample, the PRL location module 27150 can provide or interface with asystem configured to provide a patient with stimuli and to image thepatient's retina to assess topographic retinal sensitivity and locationsof preferred retinal loci. An example of such a system is amicroperimeter which can be used to determine a patient's PRL bypresenting a dynamic stimulus on a screen and imaging the retina with aninfrared camera. Another example of such a system, a laserophthalmoscope can be used to assess a retinal area used for fixation(e.g., using an infrared eye tracker) which can be used to determinediscrete retinal areas for fixation for various positions of gaze.

The PRL location module 27150 can be configured to bypass the optics ofthe patient. In some instances, optical errors induced by a patient'soptics can cause the patient to select a non-optimal PRL or a PRL whichdoes not exhibit benefits of another PRL, e.g., where a patient selectsan optically superior but neurally inferior region for the PRL.Accordingly, the PRL location module 27150 can advantageously allow theidentification of a PRL which, after application of corrective optics(e.g. the IOLs described herein), would provide superior performancecompared to a PRL selected utilizing a method which includes using thepatient's optics. This may arise where the corrective optics reduce oreliminate the optical errors which are at least a partial cause for apatient selecting a sub-optimal PRL.

The PRL location module 27150 can be configured to determine multiplecandidate locations for the PRL. The preferred or optimal PRL can bebased at least upon several factors including, for example and withoutlimitation, a patient's ability to fixate a point target, distinguishdetail, and/or read; aberrations arising from redirecting images to thecandidate PRL; proximity to the damaged portion of the retina; retinalsensitivity at the candidate location; and the like. The preferred oroptimal PRL can depend on the visual task being performed. For example,a patient can have a first PRL for reading, a second PRL whennavigating, and a third PRL when talking and doing facial recognition,etc. Accordingly, multiple PRLs may be appropriate and an IOL can beconfigured to redirect incident light to the appropriate PRLs usingmultiple zones and/or multiple redirection elements, as describedherein. For example, an IOL can be provided with two or more zones, withone or more zones redirecting light to a designated PRL, where the zonecan be configured to have additional optical power or no additionaloptical power.

The deflection module 27200 can be configured to assess the propertiesof the eye and to determine a deflected optical axis which intersectsthe patient's retina at a PRL. The deflection module 27200 can beconfigured to account for the removal of the natural lens, the opticalproperties of the cornea, the shape of the retina, the location of thePRL, axial distance from the cornea to the PRL and the like to determinethe angle of deflection from the eye's natural optical axis (e.g., theoptical axis of the natural lens, the optical axis of the eye without anIOL, etc.). In some embodiments, the deflection module 27200 can beconfigured to determine aberrations arising from deflecting incidentlight along the deflected optical axis. The aberrations can includeastigmatism, coma, field curvature, etc. The determined aberrations canbe used in the process of refining or tailoring the design of the IOL,where the IOL is configured to at least partially correct or reduce thedetermined aberrations.

The IOL modification module 27250 can be configured to determineadjustments, modifications, or additions to the IOL to deflect lightalong the deflected optical axis and focus images on the PRL. Examplesof adjustments, modifications, or additions to the IOL include, withoutlimitation, the optical systems and methods described herein. Forexample, the IOL can be modified through the introduction of a physicaland/or optical discontinuity to deflect and focus light onto the PRL. Asanother example, one or more redirection elements can be added to one ormore surfaces of the IOL to redirect at least a portion of the lightincident on the eye to the PRL. The redirection elements can include,for example and without limitation, a simple prism, a Fresnel prism, aredirection element with a tailored slope profile, redirection elementwith a tailored slope profile tuned to reduce optical aberrations, adiffraction grating, a diffraction grating with an achromatic coating, adecentered GRIN lens, etc. In some embodiments, multiple redirectionelements and/or multiple modifications can be made to the IOL, asdetermined by the IOL modification module 27250, such that thecombination of modifications and/or additions to the IOL can beconfigured to redirect incident light to different PRLs, to directincident light to different portions of the retina, to provide anoptical power which magnifies an image at the retina, or any combinationof these functions.

The IOL selection module 27270 can be configured to select the IOLdesign, power, deflection, orientation, and the like that would provideacceptable or optimal results for a particular patient. The IOLselection can be based at least in part on the patient's biometricinputs. The IOL selection can incorporate multiple considerations. Forexample, typical IOL power calculation procedures can be used to selectthe spherical IOL power which can be modified to consider the axialdistance from the cornea to the PRL. As another example, customized oradditional constants can be developed for AMD patients which providebetter results for the patients. The deflection and orientation of theIOL during implantation would be given by the PRL location.

The IOL selection can be based at least in part on ray tracing which canenable a computational eye model of the patient to be generated wherethe inputs can be the patient's own biometric data. The optical qualitycan be evaluated considering different IOL deigns and powers, beingselected that which optimizes the optical quality of the patient. Theoptical quality can be evaluated at the PRL or at the PRL and on-axis,for example.

In some embodiments, the IOL selection module 27270 can also comprise arefractive planner which shows patients the expected outcome withdifferent IOL designs and options. This can enable the patient to aid inthe decision as to the appropriate IOL design and to come to a quick andsatisfactory solution.

The IOL design system 27000 can include a communication bus 27300configured to allow the various components and modules of the IOL designsystem 27000 to communicate with one another and exchange information.In some embodiments, the communication bus 27300 can include wired andwireless communication within a computing system or across computingsystems, as in a distributed computing environment. In some embodiments,the communication bus 27300 can at least partially use the Internet tocommunicate with the various modules, such as where a module (e.g., anyone of modules 27150, 27200, or 27250) incorporated into an externalcomputing device and the IOL design system 27000 are communicablycoupled to one another through the communication bus 27300 whichincludes a local area network or the Internet.

The IOL design system 27000 may be a tablet, a general purpose desktopor laptop computer or may comprise hardware specifically configured forperforming the programmed calculations. In some embodiments, the IOLdesign system 27000 is configured to be electronically coupled toanother device such as a phacoemulsification console or one or moreinstruments for obtaining measurements of an eye or a plurality of eyes.In certain embodiments, the IOL design system 27000 is a handheld devicethat may be adapted to be electronically coupled to one of the devicesjust listed. In some embodiments, the IOL design system 27000 is, or ispart of, a refractive planner configured to provide one or more suitableintraocular lenses for implantation based on physical, structural,and/or geometric characteristics of an eye, and based on othercharacteristics of a patient or patient history, such as the age of apatient, medical history, history of ocular procedures, lifepreferences, and the like.

Generally, the instructions stored on the IOL design system 27000 willinclude elements of the methods 2900, and/or parameters and routines forsolving the analytical equations discussed herein as well as iterativelyrefining optical properties of redirection elements.

In certain embodiments, the IOL design system 27000 includes or is apart of a phacoemulsification system, laser treatment system, opticaldiagnostic instrument (e.g, autorefractor, aberrometer, and/or cornealtopographer, or the like). For example, the computer readable memory27100 may additionally contain instructions for controlling thehandpiece of a phacoemulsification system or similar surgical system.Additionally or alternatively, the computer readable memory 27100 maycontain instructions for controlling or exchanging data with one or moreof an autorefractor, aberrometer, tomographer, microperimeter, laserophthalmoscope, topographer, or the like.

In some embodiments, the IOL design system 27000 includes or is part ofa refractive planner. The refractive planner may be a system fordetermining one or more treatment options for a subject based on suchparameters as patient age, family history, vision preferences (e.g.,near, intermediate, distant vision), activity type/level, past surgicalprocedures.

Additionally, the solution can be combined with a diagnostics systemthat identifies the best potential PRL after correction of opticalerrors. Normally, optical errors can restrict the patient from employingthe best PRL, making them prefer neurally worse but optically betterregion. Since this solution would correct the optical errors, it isimportant to find the best PRL of the patient with a method that is notdegraded by optical errors (e.g. adaptive optics). Finally, the solutioncan be utilized to take advantage of the symmetries that exists withregards to peripheral optical errors in many patients.

Prior to replacing a natural crystalline lens with an IOL, an opticalpower of the IOL is typically determined. Generally, the on-axis axiallength, corneal power of the eye, and/or additional parameters can beused to determine the optical power of the IOL to achieve a targetedrefraction with a goal of providing good or optimal optical quality forcentral/foveal vision. However, where there is a loss of central visionan IOL configured to provide good or optimal optical quality for centralvision may result in relatively high peripheral refraction and reducedor unacceptable optical quality at a peripheral location on the retina.Accordingly, systems and methods provided herein can be used to tailorthe optical power of an IOL to provide good or optimal optical qualityat a targeted peripheral location such as a patient's PRL. Theimprovement in optical quality at the peripheral retinal location mayreduce the optical quality at the fovea, but this may be acceptablewhere the patient is suffering from a loss in central vision.

FIG. 30 illustrates parameters used to determine an optical power of anIOL based at least in part at a peripheral retinal location in an eye2800. The eye 2800 is illustrated with a PRL location at 20 degrees withrespect to the optical axis OA. This can represent an intendedpost-operative PRL location, where the PRL location is determined asdescribed elsewhere herein. The on-axis axial length (e.g., axial lengthalong optical axis OA) and PRL-axis axial length (e.g., axial lengthalong a deflected optical axis intersecting the retina at the PRL) canbe measured for the eye 2800 having the indicated PRL location. In somepatients, the axial length in the direction of the PRL can be estimatedfrom the measured on-axis axial length and population averages of ocularcharacteristics measured using a diagnostic instrument. The ocularcharacteristics measured using the diagnostic instrument can includepre-operative refraction, corneal power or other parameters. The cornealtopography can also be measured (e.g., measurements of the anterior andposterior surfaces of the cornea, thickness of the cornea, etc.) andthese measurements can be used, at least in part, to determine thecorneal power.

FIGS. 31A and 31B illustrate implementations of a method 2900 fordetermining an optical power of an IOL tailored to improve peripheralvision. For reference, FIG. 30 provides an illustration of an eye 2800for which the method 2900 can be applied. In addition, FIG. 29 providesa block diagram of the IOL design system 27000 which can perform one ormore operations of the method 2900. The method 2900 can be used todetermine the optical power of the IOL which improves or optimizesoptical quality at a PRL location. However, the method 2900 can be usedto determine the optical power of an IOL to be used in any suitableprocedure, such as where there is a loss of central vision, where thePRL is outside the fovea, where the PRL is within the fovea, where thereare multiple PRLs, where the PRL is at a relatively large or smalleccentricity, or the like.

With reference to FIGS. 31A and 31B, in block 2905, the on-axis axiallength is measured. The on-axis axial length can be measured, forexample, from the anterior surface of the cornea to the retina. Thelength can be determined using any number of standard techniques formaking measurements of the eye. In some embodiments, instead ofmeasuring the on-axis axial length, it is estimated based on computermodels of eyes, statistical data (e.g., average on-axis distance foreyes with similar characteristics), or a combination of these. In someembodiments, the on-axis axial length is determined using a combinationof measurement techniques and estimation techniques.

With reference to FIG. 31A, in block 2910, the PRL-axis axial length ismeasured. The PRL-axis axial length can be taken as the length along adeflected optical axis to the PRL location at the retina. The length canbe measured from the anterior surface of the cornea, from the point ofdeflection from the optical axis, or any other suitable location. Insome embodiments, the PRL-axis axial length can be estimated based on acombination of the eccentricity of the PRL, the PRL location, theretinal shape, the on-axis axial length, the distance from a proposedIOL location to the PRL, or any combination of these. In someembodiments, instead of measuring the PRL-axis axial length, it isestimated based on computer models of eyes, statistical data (e.g.,average PRL-axis axial length for eyes with similar PRL locations andcharacteristics), or a combination of these. In some embodiments, thePRL-axis axial length is determined using a combination of measurementtechniques and estimation techniques. In some embodiments, the PRL-axisaxial length can be estimated based on population averages of ocularcharacteristics measured using a diagnostic instrument, as shown inblock 2907 and 2912 of FIG. 31B. The measured ocular characteristics caninclude on-axis axial length, pre-operative refraction power, cornealpower or other measured parameters.

In block 2915, the corneal shape is determined. The anterior and/orposterior surfaces of the cornea can be determined using measurements,estimations, simulations, or any combination of these. The corneal powercan be derived or determined based at least in part on the cornealshape, that can be measured with tomography or topographic techniques.In some embodiments, the corneal power is determined based onmeasurements of optical properties of the cornea.

In block 2920, the position of the IOL is estimated. The position of theIOL can be estimated based at least in part on an estimation of alocation which would provide good optical quality at the fovea. Thelocation can be one that takes into account the corneal power ortopography and the on-axis axial length. Some other inputs that can betaken into consideration to predict the postoperative IOL position arethe axial position of the crystalline lens from the anterior cornea,which is defined as anterior chamber depth, crystalline lens thickness,vitreous length on axis combinations of thereof. In some embodiments,the estimated position of the IOL can be refined by taking into accountthe PRL-axis axial length and/or eccentricity of the PRL. In someembodiments, the estimated IOL location can take into account data fromprevious procedures, with or without including the same IOL design. Forexample, historic data from cataract surgeries can be used as that datamay indicate a good estimate of the IOL position.

In some embodiments, rather than determining an estimated initialposition of the IOL configured to provide good optical quality forcentral/foveal vision, the estimated position can be configured toprovide good optical quality for peripheral vision. Similar proceduresas described for determining the IOL position that provides with goodoptical quality on axis can be applied in this case. Therefore, thelocation of the IOL can be predicted from biometric measurements,including corneal shape or power, axial length, either on axis or to thePRL, anterior chamber depth, crystalline lens thickens and/or vitreouslength, either defined on axis or to the PRL. Retrospective data fromprevious cataract procedures aimed to restore vision on axis or at thePRL can also been taken into consideration to optimize the prediction ofthe IOL position that provide with good optical quality at the PRL. Inaddition to that, the estimated position can be based at least in parton procedures, for example, where the patient was suffering from centralvision loss (e.g., due to AMD). Similarly, data can be used where thepositions of IOLs have been tabulated and recorded as a function of theproperties of the IOLs (e.g., sphere power, cylinder power, cylinderaxis, redirection angle, etc.) and such properties were tailored usingthe systems and methods described herein. Data from such procedures canbe subjected to further selection criteria based on the location of thePRLs of the patients, where the locations were, for example and withoutlimitation, outside a determined angular range of the fovea, at aneccentric angle greater and/or less than a threshold eccentricity, at aneccentricity within a provided range of the PRL of the patient, or anycombination of these. The data can be selected based on these criteriaor other similar criteria which may improve the estimated IOL positionfor patients suffering from a loss of central vision.

In block 2925, the sphere and cylinder power of the IOL is determinedusing an IOL power calculation. The IOL power calculation can beconfigured to provide a spherical power for the IOL, a cylinder powerfor the IOL, and/or the cylinder axis, wherein the combination of one ormore of these parameters is configured to provide good or optimaloptical quality at the PRL location when the IOL is implanted at theestimated location.

The IOL power calculation can use as input data, for example and withoutlimitation, on-axis axial length (e.g., the measurement or valueprovided in block 2905), corneal power (e.g., the value determined frommeasurements acquired in block 2915), fixation angle(s) (e.g.,horizontal and vertical angles of fixation), intended post-operativerefraction, eccentricity of the PRL, eccentric axial length (e.g., fromthe anterior cornea to the location of the PRL on the retina, such asthe measurement or value provided in block 2910), predicted futuremovement of the PRL (e.g., due to progression of a disease such as AMD),a partial or full map of the retinal shape, a partial or full map of theretinal health, corneal topography, or the like. In some embodiments,the IOL power calculation is a regression formula, a theoretical formula(e.g., based on paraxial optical equations, ray tracing, etc.), or acombination of both of these. In some embodiments, current IOL powercalculation procedures can be used while considering the eccentric axiallength together with the corneal power. In those cases, A constants foreither lenses to restore vision on axis after cataract surgery can beused. In certain embodiments, specific A constants can be determineddepending on the design and/or eccentricity.

In some embodiments, ray tracing can be used to determine properties ofthe IOL which improve or reduce peripheral errors at the PRL based atleast in part on the estimated IOL position. The ray tracing canincorporate relevant measurements and data including, for example andwithout limitation, the measurements of the eye (e.g., the measurementsor values determined in blocks 2905, 2910, and 2915), the position ofthe PRL, the estimated position of the IOL (e.g., as provided in block2920), and the like. This information can be used as input in a computerexecutable module or program stored in non-transitory computer memory,the module or program configured to cause a computer processor toexecute instructions configured to perform ray tracing which can beaccomplished, for example, by the IOL design system 27000 describedherein with reference to FIG. 8. The ray tracing system can be used tofind the sphere power, cylinder power, and/or cylinder axis of the IOLto be implanted in the eye 2800, wherein these parameters are tailoredto improve or optimize for peripheral aberrations at the PRL location.Any standard ray tracing system or scheme can be used to accomplish thegoal of tailoring the sphere power, cylinder power, and/or cylinderaxis.

In some embodiments, the output of the IOL power calculation can be usedfor selecting an appropriate or suitable IOL where the output of the IOLpower calculation includes, for example and without limitation, dioptricpower, cylinder power, cylinder axis, deflection angle, and the like.These output values can be used in the selection of the IOL wherein theselected IOL has one or more properties within an acceptable range ofthe output values. In some embodiments, the IOL power calculation can beused to define or select IOL design parameters that improve or optimizeoptical quality as a function of retinal location(s) or retinal area(s).

In some embodiments, the IOL power calculation can be similar orequivalent to a power calculation configured to provide good or optimalon-axis optical quality (e.g., for central/foveal vision) where theaxial length used is the PRL-axis axial length rather than the on-axisaxial length. In some embodiments, the PRL-axis axial length can bedetermined based at least in part on the eccentricity of the PRL, thePRL location, the retinal shape, the length from the IOL to the PRL, orany combination of these. These and other input values can be determinedbased on measurements of a particular patient (e.g., the patient toreceive the IOL), a group of patients, from computer models orsimulations, or a combination of these sources. In an alternativeembodiment, both, the axial length on axis and to the PRL can beconsidered, so that the IOL selected is that which maximizes the opticalquality at the PRL and at, to some extended, at the fovea. In anotherembodiment, the axial length to several PRL can be considered, so thatthe IOL selected is that which has the characteristics that optimize theoptical quality at each PRL.

In some embodiments, the IOL power calculation can be used formultifocal IOLs for patients suffering from a loss of central vision.The IOL power calculation can be configured to provide valid andacceptable results where the PRL lies within the fovea. In analternative embodiment the add power of the multifocal IOL can beselected as that which maximizes the optical quality either at the PRLand/or the fovea.

In some embodiments, the IOL power calculation can be used inconjunction with the other systems and methods described hereinconfigured to redirect and focus images to the PRL. The powercalculations can be used to tailor the properties of the IOL, the IOLbeing used in combination with one or more redirection elements toreduce peripheral aberrations and/or improve peripheral image qualityfor patients suffering from a loss of central vision.

Additional Embodiments for Selecting IOL Sphere and Cylinder

As detailed above, IOL power is typically selected based primarily onaxial length and corneal power, and any toric parts mostly depend on thetoricity of the cornea. However, any spherical surface for which thelight is obliquely incident will exhibit a large degree of astigmatism.The embodiments below detail additional ways to properly select sphereand cylinder of the IOL for the AMD patient.

In one embodiment, sphere selection is based on population data. Here,no new biometry readings are needed. Instead, the patients areclassified depending on foveal refraction, from which the averageperipheral spherical profile for that refractive group is selected. Fromthe profile, spherical refraction at the PRL can be determined.

As seen above, sphere selection may also be based on individual data.The peripheral sphere can be determined through an axial lengthmeasurement to the PRL. This requires the modification of current axiallength methods, since the oblique incidence on the crystalline lens willmean a longer than average passage through the lens, which has a higherindex of refraction, increasing the difference between the optical pathlength and the physical length. The increased contribution can bepredicted based on PRL location.

In one embodiment, astigmatism determination is based on populationdata. The inter-subject variation in astigmatism for a given angle isrelatively modest. Therefore, the contribution of the oblique incidenceat any given eccentricity can be predicted based on PRL location. Forthese calculations, PRL location should be determined based on theoptical axis, which is on average between about 1-10 degreeshorizontally and between about 1-5 degrees vertically from the fovea.The axis of the astigmatism can also be determined from the location,e.g. for a horizontal PRL the axis is 180 and for a vertical PRL theaxis is 90, for a negative cylinder convention. Additionally, theastigmatism contribution of the IOL selected can be incorporated, in aniterative selection procedure. To this astigmatism, the cornealastigmatism from the cornea can also be added.

In another embodiment, astigmatism determination is based on individualdata. Even for persons that are foveally emmetropic, the obliqueastigmatism at e.g. 20 degrees can vary between 0.75 D and 2 D. Thereare several possible reasons for this: 1) The individual differences inangle between fovea and optical axis; 2) Individual differences incorneal power means the oblique astigmatism has different values; 3)Pupil position relative lens and cornea can be different leading tovariation in the IOL position for different individuals. Biometryreading for any or all of these parameters can then be incorporated intoan individual eye model, to select the best IOL cylinder power for thepatient.

CONCLUSION

The above presents a description of systems and methods contemplated forcarrying out the concepts disclosed herein, and of the manner andprocess of making and using it, in such full, clear, concise, and exactterms as to enable any person skilled in the art to which it pertains tomake and use this invention. The systems and methods disclosed herein,however, are susceptible to modifications and alternate constructionsfrom that discussed above which are within the scope of the presentdisclosure. Consequently, it is not the intention to limit thisdisclosure to the particular embodiments disclosed. On the contrary, theintention is to cover modifications and alternate constructions comingwithin the spirit and scope of the disclosure as generally expressed bythe following claims, which particularly point out and distinctly claimthe subject matter of embodiments disclosed herein.

Although embodiments have been described and pictured in an exemplaryform with a certain degree of particularity, it should be understoodthat the present disclosure has been made by way of example, and thatnumerous changes in the details of construction and combination andarrangement of parts and steps may be made without departing from thespirit and scope of the disclosure as set forth in the claimshereinafter.

As used herein, the term “controller” or “processor” refers broadly toany suitable device, logical block, module, circuit, or combination ofelements for executing instructions. For example, the controller 27050can include any conventional general purpose single- or multi-chipmicroprocessor such as a Pentium® processor, a MIPS® processor, a PowerPC® processor, AMD® processor, ARM processor, or an ALPHA® processor. Inaddition, the controller 27050 can include any conventional specialpurpose microprocessor such as a digital signal processor. The variousillustrative logical blocks, modules, and circuits described inconnection with the embodiments disclosed herein can be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.Controller 27050 can be implemented as a combination of computingdevices, e.g., a combination of a DSP and a microprocessor, a pluralityof microprocessors, one or more microprocessors in conjunction with aDSP core, or any other such configuration.

Computer readable memory 27100 can refer to electronic circuitry thatallows information, typically computer or digital data, to be stored andretrieved. Computer readable memory 27100 can refer to external devicesor systems, for example, disk drives or solid state drives. Computerreadable memory 27100 can also refer to fast semiconductor storage(chips), for example, Random Access Memory (RAM) or various forms ofRead Only Memory (ROM), which are directly connected to thecommunication bus or the controller 27050. Other types of memory includebubble memory and core memory. Computer readable memory 27100 can bephysical hardware configured to store information in a non-transitorymedium.

Methods and processes described herein may be embodied in, and partiallyor fully automated via, software code modules executed by one or moregeneral and/or special purpose computers. The word “module” can refer tologic embodied in hardware and/or firmware, or to a collection ofsoftware instructions, possibly having entry and exit points, written ina programming language, such as, for example, C or C++. A softwaremodule may be compiled and linked into an executable program, installedin a dynamically linked library, or may be written in an interpretedprogramming language such as, for example, BASIC, Perl, or Python. Itwill be appreciated that software modules may be callable from othermodules or from themselves, and/or may be invoked in response todetected events or interrupts. Software instructions may be embedded infirmware, such as an erasable programmable read-only memory (EPROM). Itwill be further appreciated that hardware modules may comprise connectedlogic units, such as gates and flip-flops, and/or may comprisedprogrammable units, such as programmable gate arrays, applicationspecific integrated circuits, and/or processors. The modules describedherein can be implemented as software modules, but also may berepresented in hardware and/or firmware. Moreover, although in someembodiments a module may be separately compiled, in other embodiments amodule may represent a subset of instructions of a separately compiledprogram, and may not have an interface available to other logicalprogram units.

In certain embodiments, code modules may be implemented and/or stored inany type of computer-readable medium or other computer storage device.In some systems, data (and/or metadata) input to the system, datagenerated by the system, and/or data used by the system can be stored inany type of computer data repository, such as a relational databaseand/or flat file system. Any of the systems, methods, and processesdescribed herein may include an interface configured to permitinteraction with users, operators, other systems, components, programs,and so forth.

What is claimed is:
 1. An intraocular lens configured to improve visionfor a patient's eye, the intraocular lens comprising: an opticcomprising a first surface and a second surface opposite the firstsurface, the first surface and the second surface intersected by anoptical axis, the optic being symmetric about the optical axis, whereinthe first and the second surface of the optic are aspheric, wherein theoptic is configured to improve image quality of an image produced bylight incident on the patient's eye at an oblique angle with respect tothe optical axis and focused at a peripheral retinal location disposedat a distance from the fovea, and wherein the image quality is improvedby reducing oblique astigmatism at the peripheral retinal location. 2.The intraocular lens of claim 1, wherein the image quality is improvedby reducing coma at the peripheral retinal location.
 3. The intraocularlens of claim 1, wherein the oblique angle is between about 1 degree andabout 25 degrees.
 4. The intraocular lens of claim 1, wherein the imagehas a modulation transfer function (MTF) of at least 0.3 for a spatialfrequency of 30 cycles/mm for both the tangential and the sagittal fociat the peripheral retinal location.
 5. The intraocular lens of claim 1,wherein the image has a modulation transfer function (MTF) of at least0.2 for a spatial frequency of 100 cycles/mm for both the tangential andthe sagittal foci at the fovea.
 6. The intraocular lens of claim 1,wherein the optic is a meniscus lens with a vertex curving inwards fromedges of the optic.
 7. The intraocular lens of claim 1, wherein one ofthe first or second surface comprises one or more diffractive elements.8. The intraocular lens of claim 1, wherein the optic element includesprismatic features.
 9. An intraocular lens configured to improve visionin a patient's eye where there is a loss of retinal function, theintraocular lens comprising: a redirection element configured toredirect incident light along a deflected optical axis which intersectsa retina of a user at a preferred retinal locus, the redirection elementcomprising a surface with a slope profile that is tailored such that, inuse, the intraocular lens: redirects incident light along the deflectedoptical axis; focuses the incident light at the preferred retinal locus;and reduces optical wavefront errors, wherein the slope profile istailored to redirect and focus the incoming rays on the preferredretinal locus.
 10. The intraocular lens of claim 9, wherein the slopeprofile is tailored based at least in part on a solution to ananalytical equation that is a function of a distance from the IOL vertexto the original focus (l), an index of refraction of the IOL (n_(l)), anindex of refraction of the aqueous environment (n_(aq)), an angle insidethe eye to the preferred retinal locus relative to a back vertex of theIOL (a_(p)), a radial position of the IOL (x), and/or the posteriorradius of curvature of the IOL (r), the analytical equation given by thefollowing:${{{slope}(x)} = {- {\cos^{- 1}\left( \frac{{n_{aq}\cos \; \alpha} - {n_{l}\cos \; \beta}}{\sqrt{n_{aq}^{2} + n_{l}^{2} - {2\; n_{aq}n_{l}\sin \; \alpha \; \sin \; \beta} - {2\; n_{aq}n_{l}\cos \; \alpha \; \cos \; \beta}}} \right)}}},{where}$${\alpha = {\tan^{- 1}\left( \frac{{l\; \sin \; a_{p}} - x}{{l\; \cos \; a_{p}} - r - \sqrt{r^{2} - x^{2}}} \right)}},{and}$$\beta = {\sin^{- 1}\left( {\frac{n_{aq}}{n_{l}}{\sin \left( {{\tan^{- 1}\left( \frac{- x}{l - r - \sqrt{r^{2} - x^{2}}} \right)} + {\sin^{- 1}\left( \frac{x}{r} \right)}} \right)}} \right)}$11. The intraocular lens of claim 9, wherein the redirection elementcomprises a plurality of zones, each zone having a slope profile that istailored based at least in part on the solution to an equation.
 12. Theintraocular lens of claim 9, wherein a thickness of the redirectionelement is less than or equal to 0.5 mm.
 13. The intraocular lens ofclaim 9, wherein the slope profile is tailored based at least in part onan analytical solution to an equation describing an eye of a patient.14. The intraocular lens of claim 9, wherein the slope profile istailored based at least in part on simulations performed using raytracing techniques.
 15. The intraocular lens of claim 9, wherein theslope profile is determined analytically using an equation thatincorporates an axial length to the preferred retinal locus, an angle ofthe deflected optical axis relative to an undeflected optical axis, anda radial position of the preferred retinal locus.
 16. The intraocularlens of claim 15, wherein a curvature of a posterior surface of theintraocular lens is configured to provide a focused image at the foveaof the retina of the patient.
 17. The intraocular lens of claim 9,wherein the slope profile is tailored using an iterative procedure thatadjusts a portion of the slope profile to account for a thickness of theredirection element.
 18. The intraocular lens of claim 9, wherein theredirection element is a separate, additional surface on the intraocularlens.
 19. The intraocular lens of claim 9, wherein the redirectionelement is a ring structure.
 20. The intraocular lens of claim 9,wherein the redirection element covers a central portion of theintraocular lens.
 21. The intraocular lens of claim 20, wherein thecentral portion has a diameter that is greater than or equal to 1.5 mmand less than or equal to 4.5 mm.
 22. The intraocular lens of claim 9,wherein a posterior surface of the intraocular lens includes theredirection element, and an anterior surface of the intraocular lensincludes a second redirection element comprising a plurality of zones,each zone having a slope.
 23. The intraocular lens of claim 9, wherein aposterior surface and an anterior surface of the intraocular lens areaspheric.
 24. The intraocular lens of claim 23, wherein the posteriorsurface and the anterior surface are configured to reduce astigmatismand coma in the focused image produced at the preferred retinal locus.25. The intraocular lens of claim 9, wherein a portion of the IOLincludes the redirection element and another portion of the IOL isdevoid of the redirection element.
 26. The intraocular lens of claim 25,wherein the portion of the IOL that includes the redirection element hasa different optical power from the portion of the IOL that is devoid ofthe redirection element.
 27. A method of selecting an intraocular lens(IOL) configured to be implanted in a patient's eye, the methodcomprising: obtaining at least one characteristic of the patient's eyeusing a diagnostic instrument; and selecting an IOL having an opticalpower that reduces optical errors in an image produced at a peripheralretinal location of the patient's eye disposed at a distance from thefovea, wherein the IOL is configured to produce an image by focusinglight incident on the patient's eye at an oblique angle with respect toan optical axis intersecting the patient's eye at the peripheral retinallocation, wherein the optical power of the IOL is based on the obtainedcharacteristic, wherein a first surface of the IOL is aspheric, andwherein the IOL is symmetric about the optical axis.
 28. The method ofclaim 27, wherein a second surface of the IOL is aspheric.
 29. Themethod of claim 27, wherein the obtained characteristic includes axiallength along the optical axis of the patient's eye and corneal power.30. The method of claim 29, wherein the optical power is obtained froman estimate of an axial length along an axis which deviates from theoptical axis and intersects the retina at the peripheral retinallocation, the estimate based on the axial length along the optical axisof the patient's eye and corneal power.
 31. The method of claim 27,wherein the obtained characteristic is selected from the groupconsisting of axial length along the optical axis of the patient's eye,corneal power based at least in part on measurements of topography ofthe cornea, an axial length along an axis which deviates from theoptical axis and intersects the retina at the peripheral retinallocation, a shape of the retina, and a measurement of optical errors atthe peripheral retinal location.
 32. The method of claim 27, wherein atleast one of the surfaces of the IOL includes a redirecting element. 33.The method of claim 31, wherein the redirecting element comprises adiffractive feature.
 34. The method of claim 31, wherein the redirectingelement comprises a prismatic feature.
 35. The method of claim 27,wherein the IOL is configured to provide at least 0.5 Diopter ofastigmatic correction at the peripheral retinal location.
 36. The methodof claim 27, wherein the image has reduced coma.
 37. The method of claim27, wherein the image has reduced astigmatism.
 38. The method of claim27, wherein the oblique angle is between about 1 degree and about 25degrees.
 39. The method of claim 27, wherein the IOL is configured suchthat the image has a modulation transfer function (MTF) of at least 0.3for a spatial frequency of 30 cycles/mm for both tangential and sagittalfoci.